Upon further review, there was a known issue with the initial release of the GroupWise 6.0 client, 6.5.0.
Could it be that you are using the initial relase of the 6.5 client?
Please refer to this post from 2005:
Upon review, the problem is very likely due to using the GW Client 6.5.0. As a ‘.0’ release, it had some serious issues we had to try and work around. Upon review of the code, the work-around had to use some clipboard functions and probably explains the problem you are seeing.
If you are using the 6.5.0 client, updating to 6.5.5 or 6.5.6 (which has just been released) will resolve the Stationery and many other GroupWise Client issues.