Open a command prompt at elevated level ("run as administrator"). Once it's open, type the following in the command prompt window: chkdsk h: /r
(then press ENTER). Note there is a space between the colon and the forward slash.
One of two things will happen. It will either tell you the drive needs to be dismounted before running checkdisk and ask you if that's okay. Say yes and exit the command prompt and the system should then begin checking and repairing the drive. Alternatively, it may tell you the drive needs to be checked on the next boot and ask if that's okay. Say yes, close the window and reboot. Let's see if that fixes the problem.
Edited by Allan, 16 January 2013 - 12:30 PM.