RSud's dashboard

My T60p overheats when connected to power. I have it sitting on a wooden desk without a docking station. Air flow is no encoumbered. After some use (no graphics, no games) the bottom left of the laptop becomes too hot to hold and the laptop flakes out and shutdows.

I've had this laptop for 2 years and this has just started happening in the last month.
Might be that the there is lint built up but nothing visible when I look. What is the suggested fix?