The fact other applets appear to run fine on these machine is very peculiar. Stationery makes heavy use of Microsoft Internet Explorer (as does GroupWise in terms of it’s HTML support). It might be worthwhile re-installing the latest version of IE, then re-install the GroupWise client to ensure the workstation is properly configured.
Which version of Windows are you running? I’m assuming it’s not 95/98/NT?
I look forward to hearing from you.