First of all, you need to specify what window OS is using, e.g. W98, XP, Vista?
The following steps are suggested for the corrective action:
1a. Run>CMD>chkdsk/f 1b. Select "Y"
2. Restart PC
3. DO NOT touch any keys, let system auto detect any problems. It may take few minutes.
4. When Window has loaded up, Go to "System Device", check any "Question Mark".
5. Reload any question marked "Driver" (if the Window can't auto detect the driver, Use Manufacturer (s) provided CD - driver(s), Or go to Website to find the driver from Manufacturer Website).
6. Restart PC while all drivers have been re-installed.
REMARK: Remember to right click the USB sign at the right bottom corner to release any USB device(s) before removal.