Oh. A couple other thoughts
We can confirm my guess that Windows can't identify your USB device correctly
> Open Device Manager. Is the Unknown device appearing under USB category?
> Rt click the Unknown Device, Properties->Details. Do you see USB\VID_0000&PID_0000? (Normally you should be seeing something other then all those zeroes)
> You can also try rt clicking the Unknown device select Uninstall and try connecting your USB device again
Also
1) Do try reinstalling the USB controllers and chipset drivers per earlier link
2) I've sometimes found 1000mA Usb ports helped (per earlier post) but of course don't know for sure about your case. And as they don't cost too much i also found it's been handy to have one around to be able to use & test with it for problematic USB devices
> I've found a WD Passport drive and an other device that (at least in my case) were flaky when plugged into normal USB ports but worked much better in a 1000mA hub i bought
/* EDIT */
Oh. just recalled you said you just recently did a full Windows reinstall... so trying the "reinstalling driver" link may not apply well for your case
Tho one other interesting experiment i think. Try booting into Knoppix and see if your USB drive works on your same computer under a different OS. If still consistently a problem, then would think most likely be hardware/power. See step #2 in link below for how to create a bootable Knoppix CD if you want to try that. See [post=766270]How to recover your folders/files when Windows won’t boot[/post]