I'm all out of canned air so can... "Hrumph" said Pooh.
I've sorted out other people's PCs by pulling clumps of cat hair and carpet out of the back and low and behold it stops bluescreening. Looking in side my PC I think it needs taking outside and having a hurricane blow through it.
Well if this is the problem I'm happy... But I usually find it's never just one thing with computers.