I just recently flashed my ROMs on my iPAQ 3800 with the new (and unreversable) Service Pack 3 for Windows CE. It rendered my MAMECE unusable due to not being able to find certain ROM files... Gandalf's MAME won't work either for the same reasons.
Sucks to be me eh?
Looks like a quick fix needs cooking...
By the way, to explain why I chose to flash my guts to the new SP3 - I wanted that Windows Media Player 8.5 - Seems to work very well despite feeling guilty about liking it. Handles gobs of MP3s very well, and with the controls mapped to buttons, I can track thru the collection without crashing my car.
Seems the SP3 has not affected any other applications - yet.