I noticed my iMac (Late 2009 C2D) was running a bit sluggish over the last month so I asked my Mac enthusiast buddy what I could do to help improve performance. He suggested that I use OnyX to do some system cleaning and repair permissions. I did the repair permissions (only two errors found) then headed to the cleanup section of the app. By default the program selects the following cache to clean: - Boot - International Prefs - Quicktime Components - Audio Components - Other Components After running this process I rebooted the iMac and now things are even worse. After OS X boots I can hear the hard drive working hard for about 12-15 minutes straight. During this period of time opening any application, expanding stacks in my dock, or even browsing the Web is painfully slow and gives me a beach ball with every click of the mouse. Im only using 63.97 GB of my Mac OS partition (547.61 GB total size). Also, I have no applications set to launch at boot. Any ideas what the hard drive might be doing for 15 minutes at every boot? This is a really annoying issue and I'd like to get it resolved. Thanks in advance.