Since you have TechTool Pro, I would run their S.M.A.R.T. test to see if any of the parameters are out of line. TechTool reports the individual S.M.A.R.T. values and not just the relatively useless aggregate score and the last drive I had fail passed the aggregate test, but failed one of the individual test parameters. I would also run the Surface Scan to see if there are any bad sectors on the disk. The surface scan is, by far, the best indicator of impending hard drive failure.
