We haven’t seen any reports like this. The symptoms you report could be indicative of a lack of resources. (i.e. user interface elements such as toolbar buttons dissapearing sometimes mean you are low on some resource).
Which version of Windows are you using? GroupWise is very resource hungry when it comes to certain windows resources. This can be compounded when used with a version of Windows that is resource-limited. The worst are Windows 95 and NT4.0, followed by Windows 98/ME.