Windows Server 2003/Terminal Services - DLL Caching?
Although a bit late, I am guessing that the cache is held under %Systemroot%\System32\Dllcache. This can safely be deleted (not the folder but the files itself) and repopulate.
There isn't a specified location for the user DLL but best bet is to do a quick scan under %USERPROFILE% for *.dll and see what comes up.