One thing I found when trying out different brands was one particular brand simply would not work at all on a friend's case while nothing was wrong with the flash drive itself. It simply requires more power then many usb buses even hubs supply!
Fortunately the CyberPower 4port hub bought in a local Walmart supplies enough to see one of the same brand work. Yet the other two brands in use here will simply plug in and work on anything practically suggesting individual drives/devices are the main problem.
Note I still have the 64bit RC on presently while the friend is still runing XP. Is XP the problem there? Not likely! The obvious is hardware.