Weird and urgent problem, user cannot see a view?

my users were logged off depends domain prefix

"I know this post is getting old, but I have a solution that may be useful, and wanted to share it on here in the event that anyone with the same issue may find it useful. The issue I see happen so often is when users are logged in to a Drupal website and click on certain links it would appear to log them out. A common reason for this for example would be accessing the website by typing http://example.com instead of http://www.example.com or vice versa. The issue occurs when the cookie domain for example would be set to say http://www.example.com and a user clicks on a link that is http://example.com it will not retain the cookie information and log them out. So the solution would be to change a line of code in settings.php and a couple of lines in .htaccess. First, choose when domain you will want to force people to use on you site which will be either http://www.example.com or http://example.com. In this example we will use http://example.com. Open your settings.php file which should be located in sites/default/ in your Drupal installation. Look for the this line of code

<?php
 # $cookie_domain = 'example.com';  
?>

and remove the hash symbol and change example.com to your website name .com. This will set the cookie domain to http://example.com. Now to force users to use this new cookie domain regardless if the access your website using http://www.example.com we will modify the .htaccess file. Open the .htaccess file which should be located in the root or your Drupal installation, and look for this bit of code.
<?php
# If your site can be accessed both with and without the 'www.' prefix, you
  # can use one of the following settings to redirect users to your preferred
  # URL, either WITH or WITHOUT the 'www.' prefix. Choose ONLY one option:
  #
  # To redirect all users to access the site WITH the 'www.' prefix,
  # (http://example.com/... will be redirected to http://www.example.com/...)
  # adapt and uncomment the following:
  # RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
  # RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]
  #
  # To redirect all users to access the site WITHOUT the 'www.' prefix,
  # (http://www.example.com/... will be redirected to http://example.com/...)
  # uncomment and adapt the following:
  # RewriteCond %{HTTP_HOST} ^www\.example\.com$ [NC]
  # RewriteRule ^(.*)$ http://example.com/$1 [L,R=301]
?>

un-comment these two lines of code by removing the # hash symbols and enter your website name .com in place of the example.com.

# To redirect all users to access the site WITHOUT the 'www.' prefix,
  # (http://www.example.com/... will be redirected to http://example.com/...)
  # uncomment and adapt the following:
   RewriteCond %{HTTP_HOST} ^www\.yourwebsitenamehere\.com$ [NC]
   RewriteRule ^(.*)$ http://yourwebsitenamehere.com/$1 [L,R=301]

That is all there is to it now no matter how people access your site they will always be forced to use the domain format of http://example.com and should not be logged out anymore.

*note to force users to user http://www.example.com set the cookie domain in settings.php to www.example.com and change this bit of code in the .htaccess file and change accordingly.

<?php
# To redirect all users to access the site WITH the 'www.' prefix,
  # (http://example.com/... will be redirected to http://www.example.com/...)
  # adapt and uncomment the following:
   RewriteCond %{HTTP_HOST} ^yourwebsitenamehere\.com$ [NC]
   RewriteRule ^(.*)$ http://www.yourwebsitenamehere.com/$1 [L,R=301]
?>

I hope this helps and that someone finds it useful. Happy Coding."

Found: https://www.drupal.org/node/110478 comment jjones2008