I have a user that is having an issue with multiuser calendar colors.
Example: They make appointments from different users different colors, userA with Red, UserB with Purple, UserC with Green
on random times ALL colors are gone, "sometimes" exit GroupWise and Open and it might be correct.
It is Intermittent. no pattern or actions seem to affect it.

In an effort to fix I have done this:
1. Total Patched with MS Updates
2. Purges all the Temp files in the Profile folders and in Windows\temp\
3. Removed GroupWise Client from the computer.
4. Ran the CleanIt registry cleaner.
5. Fresh install of GroupWise Client 12.0.2
It seemed great all day then the user called and said "One" calendar had no colors.
I feel it has to be something on the local PC, but what?