Hi Guys, I have a 2011 27" 3.4 17 iMac. I just got home from work and turned on my iMac to find a progress bar along side the regular apple logo during the start up. I thought this was strange because it seemed almost like it was waking from sleep. (although it was completely shut down the night before.) After about 5 minutes it loaded but i suddenly realised it was being incredibly slow and if i tried to change between spaces (or desktops as apple calls them now) i would get a lot of slow down and screen tearing. I quickly loaded up activity monitor to find that 10GB of ram was being used. Its probably also worth noting that it had not loaded any of the windows from my last session. I have since restarted the machine and the ram has returned to normal but it is still very slow all of a sudden. Any ideas as to why this might be would be great!