i had this problem for 3 months and thank to GOD it finally work and here is my solution but may not work on your.now what i did was i defrag my computer with jkdefrage,when finished restart your computer and connect your usb devices to if it may work.

Children, please. Listen to Starbat. When in doubt, blame Bill Gates. USB cables the culprit? Oh, Please!

I got the dreaded DNR message. Read these posts. Tried the unplug trick. Heh.

Finally, I did a System Restore from back before trouble started. Plugged in USB drive. Everything good. Then - a second later - the Device Not Recognized balloon popped up!!!

Of course - WINDOWS UPDATE! Windows restored me to before the trouble, USB worked fine, Windows sensed I was behind on updates due to the Restore, went out and got the Update - USB failed!!

SO, yeah, I disabled Windows Updates ... Restored again ... All is fine.

F-ing Microsoft.