Joomla 1.5.23 & Invalid Token

Are their any changes that need to be made to any of PF files with regards to Joomla 1.5.23? Since upgrading, my users are reporting a crazy amount of "Invalid Token" errors.

Please advise on ANY possible solutions to this problem, as I'm not sure at all what the fix is, but it a big headache for our users.

i am having the same problem. 50% of the time when my users try to log in they are receiving an invalid token error. if the page is refreshed they can login successfully but not all users know this and my bounce rate is way to high. please is there a fix for this?

Please open configuration.php file in Joomla root directory and try to change the secret value (you can change only one char), then all users sessions files should be inactive and created new ones.