Can't Remove Hardware Safely

Hi there.
I've been searching a lot to try to find a solution for this problem, but no success at all.
I can't remove the hardware safely. I plug it, windows reads it, I can use it. When I want to remove it, it isn't displayed at the "Safely Remove Hardware and Reject Media".
If I go to "Open Devices and Printers" windows won't find a thing too.
It's not a major problem, but I plug and unplug my 500Gb and my 1Tb WD drives and I have a lot of things there, that I'm afraid of losing.
When I insert a flash drive (not a hard drive), I can eject it somply by going to Computer, right click and Eject, but with the Hard Drives I can't.
Please help.

Problem solved.
I ran the System File Checker (SFC) and the problem was solved.

If you have the same problem, run the SFC.
Instructions: SFC /SCANNOW Command - System File Checker

Hope this solves your problem!