diff -durN webform.orig/includes/webform.pages.inc webform/includes/webform.pages.inc
--- webform.orig/includes/webform.pages.inc	2010-03-27 13:21:06.000000000 -0500
+++ webform/includes/webform.pages.inc	2010-04-26 11:31:15.000000000 -0500
@@ -70,10 +70,11 @@
   $form['submission']['submit_limit']['submit_interval'] = array(
     '#type' => 'select',
     '#options' => array(
-      '-1' => t('ever'),
-      '3600' => t('every hour'),
-      '86400' => t('every day'),
-      '604800' => t('every week'),
+      '' => t('ever'),
+      'hour' => t('every hour'),
+      'day' => t('every day'),
+      'week' => t('every week'),
+      'month' => t('every month'),
     ),
     '#default_value' => $node->webform['submit_interval'],
     '#parents' => array('submit_interval'),
@@ -200,7 +201,7 @@
   // Set the submit limit to -1 if set to unlimited.
   if ($form_state['values']['enforce_limit'] == 'no') {
     $node->webform['submit_limit'] = -1;
-    $node->webform['submit_interval'] = -1;
+    $node->webform['submit_interval'] = '';
   }
   else {
     $node->webform['submit_limit'] = $form_state['values']['submit_limit'];
diff -durN webform.orig/includes/webform.submissions.inc webform/includes/webform.submissions.inc
--- webform.orig/includes/webform.submissions.inc	2010-03-25 19:50:35.000000000 -0500
+++ webform/includes/webform.submissions.inc	2010-04-26 11:32:30.000000000 -0500
@@ -408,6 +408,41 @@
 }
 
 /**
+ * Get the timestamp representing the next allowed time for a user submission.
+ */
+function _webform_submission_interval_timestamp($node) {
+  // Get default timezone using code borrowed from drupal 7 function.
+  global $user;
+  if (variable_get('configurable_timezones', 1) && $user->uid && $user->timezone) {
+    $tz = $user->timezone;
+  }
+  else {
+    // Default to timezone setting from date_default_timezone_set(), php.ini or failover to UTC
+    $tz = variable_get('date_default_timezone', @date_default_timezone_get());
+  }
+  // Set the timezone used for the following operations.
+  date_default_timezone_set($tz);
+  // Calculate our submission limit expiration based on current time values.
+  switch ($node->webform['submit_interval']) {
+    case '':
+      return 0;
+    case 'hour':
+      return time() - 3600;
+    case 'day':
+      return mktime(00, 00, 00, date('n'), date('j'), date('Y'));
+    case 'week':
+      // Adjust day of the week according to the site settings.
+      $day_of_week = date('w') - variable_get('date_first_day', 0);
+      if ($day_of_week < 0) {
+        $day_of_week = $day_of_week + 7;
+      }
+      return mktime(00, 00, 00, date('n'), date('j') - $day_of_week, date('Y'));
+    case 'month':
+      return mktime(00, 00, 00, date('n') - 1, date('j'), date('Y'));
+  }
+}
+
+/**
  * Check if the current user has exceeded the limit on this form.
  *
  * @param $node
@@ -429,8 +464,8 @@
            "WHERE (( 0 = %d AND remote_addr = '%s') OR (uid > 0 AND uid = %d)) " .
            'AND submitted > %d AND nid = %d AND is_draft = 0';
 
-  // Fetch all the entries from the database within the submit interval with this username and IP.
-  $num_submissions_database = db_result(db_query($query, $user->uid, ip_address(), $user->uid, ($node->webform['submit_interval'] != -1) ? (time() - $node->webform['submit_interval']) : $node->webform['submit_interval'], $node->nid));
+  $submitted_timestamp = _webform_submission_interval_timestamp($node);
+  $num_submissions_database = db_result(db_query($query, $user->uid, ip_address(), $user->uid, $submitted_timestamp, $node->nid));
 
   // Double check the submission history from the users machine using cookies.
   $num_submissions_cookie = 0;
@@ -439,9 +474,9 @@
 
     if (isset($_COOKIE[$cookie_name]) && is_array($_COOKIE[$cookie_name])) {
       foreach ($_COOKIE[$cookie_name] as $key => $timestamp) {
-        if ($node->webform['submit_interval'] != -1 && $timestamp <= time() - $node->webform['submit_interval']) {
+        if ($timestamp <= $submitted_timestamp) {
           // Remove the cookie if past the required time interval.
-          setcookie($cookie_name . '[' . $key . ']', '', 0);
+          unset($_COOKIE[$cookie_name][$key]);
         }
       }
       // Count the number of submissions recorded in cookies.
diff -durN webform.orig/webform.install webform/webform.install
--- webform.orig/webform.install	2010-04-09 21:20:38.000000000 -0500
+++ webform/webform.install	2010-04-26 11:52:53.000000000 -0500
@@ -71,10 +71,9 @@
         'default' => -1,
       ),
       'submit_interval' => array(
-        'description' => 'The amount of time in seconds that must pass before a user can submit another submission within the set limit.',
-        'type' => 'int',
-        'not null' => TRUE,
-        'default' => -1,
+        'description' => 'The amount of time that must pass before a user can submit another submission within the set limit.',
+        'type' => 'varchar',
+        'length' => 32,
       ),
     ),
     'primary key' => array('nid'),
@@ -1148,10 +1147,39 @@
   return $ret;
 }
 
+/** This entry is nullified due to reversion
+ * between 3.0-beta4 and 3.0-beta5.
+ */
+function webform_update_6316() {
+  $ret = array();
+  $ret[] = array('success' => TRUE, 'query' => t('Null update no changes have been made.'));
+  return $ret;  
+}
+
+/**
+ * Convert the submission interval to a string instead of an an integer.
+ */
+function webform_update_6317() {
+  $ret = array();
+  db_change_field($ret, 'webform', 'submit_interval', 'submit_interval', array('type' => 'varchar', 'length' => 32));
+  $intervals = array(
+    '-1' => '',
+    '3600' => 'hour',
+    '86400' => 'day',
+    '604800' => 'week',
+  );
+
+  foreach ($intervals as $seconds => $interval) {
+    $ret[] = update_sql("UPDATE {webform} SET submit_interval = '$interval' WHERE submit_interval = '$seconds'");
+  }
+
+  return $ret;
+}
+
 /**
  * Remove the Webform Debug variable.
  */
-function webform_update_6316() {
+function webform_update_6318() {
   $ret = array();
   variable_del('webform_debug');
   $ret[] = array('success' => TRUE, 'query' => t('Removed the webform_debug variable which is no longer used.'));
diff -durN webform.orig/webform.module webform/webform.module
--- webform.orig/webform.module	2010-04-11 01:13:51.000000000 -0500
+++ webform/webform.module	2010-04-26 11:33:41.000000000 -0500
@@ -852,7 +852,7 @@
   module_load_include('inc', 'webform', 'includes/webform.components');
 
   // Insert the webform.
-  db_query("INSERT INTO {webform} (nid, confirmation, confirmation_format, redirect_url, teaser, allow_draft, submit_notice, submit_text, submit_limit, submit_interval) VALUES (%d, '%s', %d, '%s', %d, %d, %d, '%s', %d, %d)", $node->nid, $node->webform['confirmation'], $node->webform['confirmation_format'], $node->webform['redirect_url'], $node->webform['teaser'], $node->webform['allow_draft'], $node->webform['submit_notice'], $node->webform['submit_text'], $node->webform['submit_limit'], $node->webform['submit_interval']);
+  db_query("INSERT INTO {webform} (nid, confirmation, confirmation_format, redirect_url, teaser, allow_draft, submit_notice, submit_text, submit_limit, submit_interval) VALUES (%d, '%s', %d, '%s', %d, %d, %d, '%s', %d, '%s')", $node->nid, $node->webform['confirmation'], $node->webform['confirmation_format'], $node->webform['redirect_url'], $node->webform['teaser'], $node->webform['allow_draft'], $node->webform['submit_notice'], $node->webform['submit_text'], $node->webform['submit_limit'], $node->webform['submit_interval']);
 
   // Insert the components into the database. Used with clone.module.
   if (isset($node->webform['components']) && !empty($node->webform['components'])) {
@@ -885,7 +885,7 @@
   }
 
   // Update the webform entry.
-  db_query("UPDATE {webform} SET confirmation = '%s', confirmation_format = %d, redirect_url = '%s', teaser = %d, allow_draft = %d, submit_notice = %d, submit_text = '%s', submit_limit = %d, submit_interval = %d where nid = %d", $node->webform['confirmation'], $node->webform['confirmation_format'], $node->webform['redirect_url'], $node->webform['teaser'], $node->webform['allow_draft'], $node->webform['submit_notice'], $node->webform['submit_text'], $node->webform['submit_limit'], $node->webform['submit_interval'], $node->nid);
+  db_query("UPDATE {webform} SET confirmation = '%s', confirmation_format = %d, redirect_url = '%s', teaser = %d, allow_draft = %d, submit_notice = %d, submit_text = '%s', submit_limit = %d, submit_interval = '%s' where nid = %d", $node->webform['confirmation'], $node->webform['confirmation_format'], $node->webform['redirect_url'], $node->webform['teaser'], $node->webform['allow_draft'], $node->webform['submit_notice'], $node->webform['submit_text'], $node->webform['submit_limit'], $node->webform['submit_interval'], $node->nid);
 
   // Compare the webform components and don't do anything if it's not needed.
   $original = node_load($node->nid);
@@ -987,7 +987,7 @@
       'submit_notice' => 0,
       'submit_text' => '',
       'submit_limit' => -1,
-      'submit_interval' => -1,
+      'submit_interval' => '',
       'roles' => array(1, 2),
       'emails' => array(),
     );
@@ -1235,10 +1235,10 @@
 
   // If the user has exceeded the limit of submissions, explain the limit.
   elseif ($limit_exceeded && !$cached) {
-    if ($node->webform['submit_interval'] == -1 && $node->webform['submit_limit'] > 1) {
+    if ($node->webform['submit_interval'] == '' && $node->webform['submit_limit'] > 1) {
       $message = t('You have submitted this form the maximum number of times (@count).', array('@count' => $node->webform['submit_limit']));
     }
-    elseif ($node->webform['submit_interval'] == -1 && $node->webform['submit_limit'] == 1) {
+    elseif ($node->webform['submit_interval'] == '' && $node->webform['submit_limit'] == 1) {
       $message = t('You have already submitted this form.');
     }
     else {
@@ -1816,11 +1816,13 @@
     $form_state['values']['details']['is_new'] = TRUE;
 
     // Set a cookie including the server's submission time.
-    // The cookie expires in the length of the interval plus a day to compensate for different timezones.
+    // The cookie expires in the length of the interval plus a day to compensate
+    // for different timezones.
     if (variable_get('webform_use_cookies', 0)) {
       $cookie_name = 'webform-' . $node->nid;
-      $time = time();
-      setcookie($cookie_name . '[' . $time . ']', $time, $time + $node->webform['submit_interval'] + 86400);
+      $time = $submission->submitted;
+      $next_allowed_time = _webform_submission_interval_timestamp($node);
+      setcookie($cookie_name . '[' . $time . ']', $time, $next_allowed_time + 86400);
     }
 
     // Save session information about this submission for anonymous users,