I high pitched sound coming from and hard drive is normal and abnormal.. it depends if its supposed to make that noise. Okay so that answers nothing but! Crack open the case and listen to see if the sound is coming from the drive at all. I had such sounds seem to come from drive activity (like hissing or high pitched sound) but really ended up being created in the power supply. Go Figure.
If the sound is coming from the drive, and it didn't make that noise before (as in you owned it for a month and its happening now)... I suggest taking a trip to western digital and downloading a diagnostics program or getting one from else where. Still even if the program says its okay, keep and eye on it er ear, be sure to backup all data.
When my computer made the high pitched sounds accessing things it did it ONLY in windows when waterfall pro or other cpu cooling tools were activated? Ask youself this, does it make the sound when windows or unix variant is loading?