Outlook closing without prompt or error

I have 3 machines running windows nt 4.0 sp6a and Office XP standard. I recently installed all service packs and security updates from Microsoft to those machines. Since the installs Outlook will just close without prompt or error. If Word is used as the editor it continues to run after opened as a service by outlook. I have taken off Word as the editor for replys and composing. I have also tried renaming the Extend.dat file incase it had corrupted. Nothing seems to work. Has anyone else had similiar issues? If so is there a correlation with the updates? And is there a solution?