i have a900-0010-01 rev. i was running both usb and ps/2 together. thats how it was in the ultracade. i just tried one at a time. it was better with just the ps/2, but the joystick would still lock up. as for the ultracade, one day it wouldnt get out of the dos like boot mode. i do have the cds and the serial numbers so i tried booting it from the cd. it would just stop dead. i went in with a keyboard and really killed it. i reset something to the effect of restore defaults, then it wouldnt start up at all. i brought it to a computer repair guy, but he couldnt get it to boot. i thought i couldnt change any of the hardware. so i figured it was dead forever. it is a cool machine. i liked how dummy proof it is. just give it power and its ready to go. i do want to build a mame cabinet, but my boys were really happy with the ultracade. if i can find out how to boot it, maybe i should get another hard drive. if not then get the mother board and chip. any info would be great. thanks, mike