As I said, I have a 27 month old Macbook Black. For about 9 months or so it's been suffering from RSS. The episodes only occur if I'm streaming video online, or running graphics-heavy games while doing something else like playing video or running Transmission. Sometimes to avoid the random shutdowns I'll sit it on an ice tray. Up until a few days ago, that would prevent the shutdowns. But, not anymore. My mac has all of it's original hardware, and I've made no upgrades. If I use it lightly (web browsing, word processing) I have no problems and the machine doesn't run as hot. But, as I'm sure you can imagine I rarely use my mac lightly. I'm not sure what the problem is exactly. At first, I thought I needed more RAM. Then I thought the heat sink needed to be replaced. Now, I'm wondering if the problem can be corrected by simply reapplying the thermal paste. But, before I purchase anything I just wanted to get some feedback. Has anyone else been in a similar situation? Any thoughts as to what could be the problem? I'm a DIY kinda guy, so please don't tell me just to send it into Apple. If you need any additional information (specs, etc.) I'll be happy to post them. Thanks in advance for any and all help!