Temporary files on a terminal server are always a problem for server admins as it can waste gigabytes worth of hard disk space. I have found a command line utility that can clear temporary files from all users.
The program is called ICSweep and is available from http://www.softpedia.com/get/System/System-Miscellaneous/ICSWEEP.shtml
Basically to clear all temp files you just need to open a command prompt change to the location of the exe. and run icsweep.exe /all it will now go through all users and clear temp files.