I've got a "friend" *cough* who had an illegal copied version of Office 2000. He installed it initially, and it ran fine. However, when my "friend" upgraded it with the service pack, it exhibitted the same exact symptoms. The application would open fine, the application would display for 1/2 of a second, and then close.. no error, no beep, no nothing. I had to .. er, my "friend" had to uninstall the program, and re-install, minus the service pack. Worked fine after that, but my suspicion is that it was a copy-protection scheme build into SP-1 that caused it to do this.
I realize you are having the same symptoms under different circumstances, but maybe in your case, it's also a copy-protection problem? Just a guess...