I wouldn't necessarily move to 2003 as 2007 looks really promising and if you wait a little while until the first, or second, service packs come out I think you will be better off than going with 2003. In fact 2007 lets you work with all versions 97 and above AND keep them in their original format (no conversion necessary and it doesn't screw anyone up that works on it with a lesser version).
Now about your problem - do you have all of the Windows and Office service packs installed? Also, does this happen to just one database, or all? If just one, try importing everything into a new, blank database.