The MBP is about 6 months old (purchased it in May) and always ran without any issues.. But this week, I wanted a bit more 'speed', as I was experiencing too much (for my taste) beachballs, so I upgraded the memory and HDD. It originally had a 250GB Seagate, but as I don't really trust that brand I immediately replaced it with a Western Digital Scorpio Blue 320GB. This week I went to a WD Scorpio Black 500GB and 2x4GB Corsair 1066MHz DDR3. Didn't notice much issues for a few days, but I have to admit that I hardly used it during that period. I went to a concert on Friday and made some videos that I wanted to edit in iMovie. While exporting the movie the first KP occurred. There were 3 lines on screen and no message indicating that I have to use the power button to shut down the system. The KPs I got after that did have the message, sometimes with and sometimes without the 3 lines. They seemed to be 'flickering' a bit and sometimes I saw a big white bar about halfway on my screen. After the 1st KP the MBP refused to boot and gave me a beepcode (3x short, 3x long, 3x short), but after a 15 min rest it worked again. Because of the (white) lines I first suspected some kind of heat problem, so I decided to install SMCFanControl and push the fan to 6200rpm. I didn't mind the noise if that would make the system more stable during testing, but it didn't. I've been searching around for about 2 days now as to what is causing these KP's. I did a fresh SL install on the 500GB Black and then restored my data from a Time Machine backup. I read that some people have issues with this so I'm thinking of putting my 320GB Blue back in and testing with that. The small data-loss isn't much of a problem, the movies are still on my iPhone, I'll just lose all the editing I did on them. (Which wasn't much ) I uploaded the logs: Nr.1 -- Nr.2 -- Nr.3 Nr.2 is incomplete, apparently it couldn't 'save' the entire KP log. Maybe I pressed the power button too quickly? Earlier today I took out the ram to replace it with my original 2x2GB, and then renembered that some people on a Dutch forum suggested to run the Apple Hardware Test and Rember to check the memory. So I reseated them and ran both tests, without any problems. I did them 2x and it turned out to be OK. I've been randomly 'editing' stuff in iMovie and exporting every 2 minutes, so far no problems. It used to KP while exporting the 2nd/3rd movie, I've done 4 without problems now. Maybe there was a problem with the original placing of the memory?