Thanks for reading! It's been a while since I've posted here. Just looking for any help regarding the issue. My MacBook is now getting pretty old, but still does the job so I'm reluctant to get rid of it. The problem is the CPU is heating up excessively, and will at times just stop working by going black and shutting off. Normally by closing the lid, leaving it five minutes and reopening I find it's only gone to sleep and will come back on. But, sometimes it's completely shut down and I have to reboot. This normally happens when streaming online, either with flash or silverlight (use for Sky Go), but normally runs pretty hot with minimum usage. It's been running Snow Leopard for a long time and the system has become rather clogged up. I've been reluctant to do a Time Machine Backup and restore as I thought it might have been something software based (lots of junk over the last couple of years since I last did a fresh install and didn't want a software problem just to be transferred over) and have only just got round to doing a backup and fresh install of Lion, which I was hoping would solve the issue, but it hasn't. I've literally just finished the fresh install of Lion and installed iStat Pro to check the temperature and the fans are running at full power and the temperature is running at 85ºC! Nothing much running on Activity Monitor (itself using the most of the CPU, around 8%) so now I'm a little bit stuck. I've obviously got rid of ay chance of the problem being software based and starting to think it's hardware based. Does anyone know what the problem could be? Fans clogged up with dust? I've read somewhere about some kind of heat sink paste? Any ideas? Any help would be really appreciated!