This problem of mine is somehow unique, as I didn't find anything on the web that solves this.
Recently I've upgraded from WinXP to Windows 7 ultimate. I have in my possession an external Verbatim HDD (500GB) that I use to backup my stuff.
When connecting the HDD the device is installed and you can see it in "My Computer" with the other drives.
After about 20 seconds, or when I try to copy data into the HDD, windows says "USB Device Not Recognized" and stopps displaying it as a drive.
In the Device Manager, I get the "Unknown Device" in the relevant USB port. Surely, I used all my ports to verify this issue.
As it appears, this only happens in Windows 7, not in previous versions of windows.
Can someone PLEASE help me get through this crisis ?