Data Selection Issues

We are experiencing an issue with random applications in a Citrix environment (XP), and randomly on various servers (we have 1 in a farm). Users are unable to select some of the parameters in the data selection of the app they are in. When they logout and back in (usually hitting a different server, the issue disappears. We suspect this is related to XP somehow, but can't verify this. Any help is greatly appreciated.

Are you referring to UBE or application....I seen this before with UBE's in Meta Frame 1.8 and that happened if a citrix user on the server had the version checked out in the PROD environment. Once they check the version was checked in then the issue went away.