Have you tried device manager to see if any yellow exclamation marks beside any of the devices. No harm in trying one of the security programs mentioned just in case. Or download and try Driver Max its free and will tell you if any of your drivers are needing updated. Could it be a faulty memory stick.I know nothing of this just what I have read on other threads.If you have 2 memory sticks take one out and see if the computer runs ok then take that one out and put the other one in and try that. A lot of updates from Microsoft last night maybe one of those might have helped.