From those couple of screenies, you can clearly see there is some issue with your WD Caviar drive, the 750gb drive scores are more in line with expected results, so if there is any way you can grab the stuff from your drive that you need to keep off it, ie your steam saves, or check whether your cloud sync on steam is upto date, then perhaps try a fresh format of the 2TB drive and rerun, else look into a checkup with WD and see what they have to say. iirc black drives have a 5 year warranty. would be worth a looksie.