I'll try be brief. My macbook pro 2008 unibody, kept asking me to shut down, if you kept pressing cancel it would wait, and ask again... and repeat until it just turned it self off. After it would boot to different times then shut down. But never functional. It seemed like a thermal problem, so cleaned fans, changed thermal paste, still same problem. I disconnected the thermal sensor and now it works fine.
Right, the only problem I can really imagine is the fans wearing out i've set the base speed to 3,500 RPM (max in Fan Control). Too poor to get it looked at/fixed by a professional, also too poor for new Logic Board.
TLDR: I removed my thermal sensor, what problems are going to happen.