I've had no stability problems whatsoever in W98SE or W2k pro when playing Aces High. And take into notice this is with heavily overclocked computer using NED's.. LOL
Only lockups have happened when hosting h2h games, even those are now gone due to patching.
WinME could be the cause of your problem, I havenīt heard anything good about it.
OTOH if you have random system errors, flickering windows etc. crap, there is a strong chance your problems are in hardware not software. Try a CLEAN reinstall of the whole operating system and drivers (I hope you have partitioned C: for system files only
), if that won't fix the problems, I'd start looking for the reason in hardware setup. Might be something as simple as false agp bus speed or irq conflict.