Invisible man,
I have Windows 98, and it happens to me too.
Usually when i try to open several windows at once (Right click on link and Open in new window.) When it freezes I Ctrl-Alt-Del and try to close it from there. Thats where i get the NOt responding message.
After i end the task I get a run time automation error...and all works out fine!
Something which might be related is MSN Messenger. It often takes ages to load after password.