A couple of times in the last 2 weeks, I've had problems re-booting my Toshiba laptop.
I quite often get IE8 freezing and this is usually solved by restarting the PC but twice recently it won't restart and just keeps powering off.........if I leave it for a few hours it restarts with no problems.
Figure out which way it sucks and blows (so to speak) and suck it with the vacuum the opposite way otherwise you'll just be pulling any fluff deeper into the heat sink.