Hi Jeremy,
There is a chance that this could be a hardware failure. When was the last time that you were able to use your flash drives? Let's try to run the hardware troubleshooter and check if it finds anything. Go to Control Panel > Change view to Small icons > Troubleshooting > Hardware and Sound > Configure a device. You can also go to Device Manager > Scan for hardware changes. Note that you have to do this steps while the flash drive is plugged in.
Let us know how it goes.