Can not log in at all

Yesterday I was working with Webform module with arrange_fields, in my local site under construction with the admin user. Suddenly, appeared the access denied message. I tryed to log in again and it have been impossible. I'm using the ?q=user page to log.

My server is Xampp for Linux 1.7.7: Apache 2.2.21, php 5.3.8, mysql 5.0.8 running on an Ubuntu lucid 10.04 OS
My drupal configuration is: Core D 7.14 - corporative_site profile
I added these modules: arrange_field, ckeditor_swf, field_group, filedepot, filefield_paths, imce_wysiwyg (not active), media, media_browser_plus, menu_attributes, menu_minipanels, menu_views, node_convert, panels, plupload, references, rotating_banner, rules, search_config, shadowbox, styles, tcpdf, views_slideshow_xtra, wysiwyg (not active).

I did this to try to fix the problem: (not in order, mixing several of this)

* Change the password via phpmyadmin.
* Truncate all the cache tables, watchdog, flood, and session.
* Comment and uncomment the $cookie_domain line in settings.php
* Fix the $base_url line in settings.php
* Desactivate filedepot and arrange_fields modules via phpmyadmin.
* Run the update.php script
* Erase the content in the cache folder for Chrome. I don't know why Chrome don't clear the navigation data from the browser.
* Create a new user only with a registered role and log in using other web browser (Firefox and Opera)

This is the three time that i have this issue in this month. The first time I added the $GLOBALS['tempUser'] = $user; at bottom of index.php file, updated the Drupal core and nothing worked. Finally, I had to reinstall and lost all my work. http://groups.drupal.org/node/200283#comment-756848

The second time, the problems started in the CKFinder module, and I could fixed uncommenting the $cookie_domain line (or viceversa, I don't remember).

Now, I have been looking for an answer during more than 10 hours, without success.

I'm late in my project for this issue and I can not risk to have this issue in the production site. I need help because I don't have anymore ideas, except give the admin role to the default user, it works, but it is not secure in a production site.