Hex Strings Appended to Pathnames

Operating System: CentOS 4.6 PHP Version: 4.3.9-3.22.9 Zend Optimizer (free) version: 3.2.6 Hello. I've got somewhat of a strange problem here involving Squirrelmail. Basically, what is happening is that one of our customers is logged out of his Squirrelmail session at random intervals. This can occur when he goes to read an email or, after composing an email, when he clicks on the Send button. The following log entries correspond with those times that the customer is logged out. [error] [client X.X.X.X] File does not exist: /var/www/squirrelmail/src/redirect.php3a5def33 [error] [client X.X.X.X] File does not exist: /var/www/squirrelmail/src/redirect.php29e09f87 [error] [client X.X.X.X] File does not exist: /var/www/squirrelmail/src/move_messages.phpf9f96dfb [error] [client X.X.X.X] File does not exist: /var/www/squirrelmail/src/redirect.phpdc6cc80a So what would be the cause of appending those hex strings to those pathnames? Cheers, Mick