I have replaced the controller before, and even moved the plates to another HDD, but it is not an easy task. Listen to Omegae...if you can access windows or whatever OS, get all your files backed up, maybe do a files and settings transfer and get a new one ASAP. If you have another puter, you can hook the old drive up as slave and do a deep test of the HDD, run check disk and what not. You can also start the PC with a UBCD and use HDTune to see if about what errors occours. Good Luck!