Everything freezing / working very slowly
I've been away for about 2 weeks, & since I got back & switched on my Mac, nothing seems to work properly; Firefox, Bridge & Photoshop are all seizing up; freezing, sticking, not reacting when I type, or taking several minutes to react. Almost everything I try to do involves watching that beach ball spinning round for several minutes. Anyone got any idea what this is? is it a bug? I removed Norton as it was driving me crazy with it's incessant pop-up messages, but maybe I should re-install it? I installed something else instead that was recommended here - ClamXav? I've installed updates for the Mac.
iMac, Mac OS X (10.7)