The usual suspects for that error message are all bad.
Failing HDD, failing optical drive, failing motherboard, dodgy cables (unlikely), dodgy PSU (unlikely).
I can imagine by now that you understand that there is a 99% chance that its hardware based, and the usual suspect is the HDD, the next most likely is the motherboard, and the optical drive.
If you have a second PC, take the HDD out and back it up onto your other PC, otherwise back it up via DVD/CD. You will probably find that you dont get the same error when the drive is attached to the other PC, as its not booting from it, and most likely the only part of the drive that is failing is the boot sector.
If your drive is a WD replace it, if its any other make download and run the diagnostic tools, they will give you a fault code, and if its under warranty you can have it replaced.
Main PC, P180, CM Silent Pro 500M, i5 3570k @ 4.2Ghz, 8-GB @ 2,000MHz, 256 GB Samsung 830, 500-GB 7K500, MSI 660Ti Twin Frozr, PC is super quiet :o
Server, 6-TB RAID-5 array, + 2 x 2-TB backup drives, 380W Enermax Pro82+, 4x very quiet fans, positive pressure only, no exhaust fans
Living Room PC, 3500+, 2-GB RAM, HD501LJ