Usb external drives not recognized

[Maguscreed]

This problem just popped up on both my win 7 machines.
Powered usb external drives (the ones that are based on standard hard drives and plug into the wall) are recognized, but the smaller usb powered ones are not.
The drives work on the same computers when booted xp so it's not the usb itself.
Any ideas?

 

[TVeblen]

Give this a try: Turn OFF "USB Selective Suspend" and test.
http://www.sevenforums.com/tutorials/147369-usb-selective-suspend-turn-off.html

 

[gregrocker]

Try also updating the Enhanced USB host controller.

Make sure your Win7 updates are current, including any newer optional drivers.

Update then run a full Malwarebytes scan.

Run the SFC -SCANNOW Command

Check the logs for repeat errors and use the System Resources in these troubleshooting steps.

As a last resort before reinstall try a Repair Install