Other users credentials being remembered in Safari

Question

We are using Snow Leopard on the Macs and are bound to OD and AD, when the users login and open Safari they do not get asked to authenticate to the proxy server and are using cached credentials that are allowing them to connect to banned sites, how do I get rid of the cached credentiaals.
I have already deleted the browsing history and cache.I have deleted the keychain and the users cache. Ihave deleted the PubSub folder contents and the Safari folder contents in their home directories.
Can anyone tell me where else I can look for the cached credentials

Answer 1

I'm sure the store could fix it, but I think we should start with this...
"Try Disk Utility
1. Insert the Mac OS X Install disc that came with your computer, then restart the computer while holding the C key.
2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu. (In Mac OS X 10.4 or later, you must select your language first.)
Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.
3. Click the First Aid tab.
4. Click the disclosure triangle to the left of the hard drive icon to display the names of your hard disk volumes and partitions.
5. Select your Mac OS X volume.
6. Click Repair. Disk Utility checks and repairs the disk."
http://docs.info.apple.com/article.html?artnum=106214
Then Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot.
The usual reason why updates fail or mess things up, is if Permissions are not fixed before & after every update, with a reboot... you may get a partial update when the installer finds it doesn't have Permissions to change one obscure little part of the OS, leaving you with a mix of OS versions.
Some people get away without Repairing Permissions for years, some for only days.
If Permissions are wrong before applying an update, you could get mixed OS versions, if Directory is the slightest messed up, who knows!
If many Permission are repaired, or any Directory errors are found, you may need to re-apply some the latest/biggest updates again, or even do an A&I if you have enough free disk space.
An Archive & Install, which gives you a new OS, but can preserve all your files, pics, music, settings, etc...
http://docs.info.apple.com/article.html?artnum=107120