Base Unit Symptoms

Click on the sentence below which best describes the problem with the system.

I cannot access my hard drive(s) properly.
Hard drive dead, 'Error reading drive C', 'Track 0 not found'
Directories or files are lost or damaged
My hard drive is going excessively slow.
Sector Not found
I have an HDD > 528 Mb, but I cannot access anything after the first 528 Mb.