Thanks guys!
Connections look good on the trackball unit. I can't spot and bends or frays, loose or exposed wires/connections, etc.
No I am not using a self powered hub. Did consider it though, one that's self powered. I checked my usb bandwidth consumption and it's zapping about 23%. More than twice my other little Logitech trackball mouse... And yes I did remove the Logitech software. So your right, definitely a hungry little device! Also I did try hooking it up as the only USB device. Same prob!
But I may have sorted the prob! What I have done since last checking here is to disable the "error detection" on my usb host controllers from the device manager. So far I've had my box running just over half a day now since doing that, and the Happs trackball has been stable. So it's looking like that might've fixed the issue.

If not, I will definitely give the "Self Powered
hub a try!
BTW urrebelscum! Good damn work with your MAMEanalog+! I love it!