Chkdsk didn’t seem to do anything.
I replaced the drive with a Seagate and, (edit) - it developed a similar problem too, although not seeming to occur as frequently. I think I have now figured out the issue. I was noticing my computer was going into hibernation mode even when the power profile was set never to hibernate. Looking at the event log I saw the following at the time of the hibernation - “The system firmware has changed the processor’s memory type range registers (MTRRs) across a sleep state transition (S4). This can result in reduced resume performance.” At around the same time was the following message - “Process C:\Program Files\ATI Technologies\ATI.ACE\a4\AdaptiveSleepService.exe (process ID:6572) reset policy scheme from {381b4222-f694-41f0-9685-ff5bb260df2e} to {381b4222-f694-41f0-9685-ff5bb260df2e}.”
If you google AdaptiveSleepService you will see a bunch of people having issues with this service. I have disabled that process and have not had my computer hibernate improperly, nor have I had the disk slowdown issue, since then. I haven’t plugged the WD drive back in to be 100% sure this will fix the problem I was having on the WD drive, but I suspect it would.
