In the last week, I've noticed my computer started acting odd.

I'm running Windows 7 Pro. Computer is custom build (built in Dec. 2010), Intel Core i5-760, G.Skill 8 Gig RAM, 4 Hard drives all Seagate Barracuda. At the moment, I can hear the hard drive constantly spinning as if it's constantly reading something. Performance is sluggish when trying to access some of the hard drives. For AV, I'm running McAfee.

However, when I check Task Manager, there's nothing running that would account for over 6 gigs of RAM being used. Is this just the ultimate fate of Windows 7 (which has never caused me any problems before, unlike prior Windows)? Or is there some other possible problem, I'm not seeing? Any help/advice would be greatly appreciated.

TaskMgr.jpg
RAMperf.jpg

I should also mention, this problem disappears temporarily if I reboot the computer. At some random point, usually a day or two later, this problem returns.