Check this article out;
Database and Registry Size Grow due to Microsoft Licensing
http://support.citrix.com/kb/entry.jspa?externalID=CTX717362
Evan Mann wrote:
I have a 198meg default registry hive on a 2000 SP4 TS server. Is there some effective way to greatly reduce this? I'm having major issues getting users logged in because of registry size keeps bumping up against the maximum