I have the same trouble with my week old Treo Pro and GroupWise PDA Connect.
This
post recommends delete or rename the /windows/230 directory. I tried to remove this directory and it told me that it was locked. I renamed the folder and I was able to reinstall GroupWise PDA connect and sync. When it did sync it was treated as a new device and I had to do a full sync, overwritting all of my pocket pc records with GroupWise records.
**edited to include link that was referenced.**