It could be a RAM issue Try this application and test the RAM http://kelleycomputing.net/rember/ Run it on loop to check for intermittent problems. If not if could be a logicboard problem. Common signs with logicboard problems are freezing and beachballing. But first try the RAM test and see if its that

Tried the alternative user account, still very buggy, in new projects and existing ones. the most recent thing that went on was a drive partition with win7 n boot camp, but it was ok for a bit after that so i dont know. my other H/ware is focusrite saffire pro 26 and an M-audio keystation pro 88. Im goin to remove the partition, see if that has an effect then try the logic upgrade. I installed everything from a fresh format of the main drive. cheers