My SL screen has gone insane!!

Well probably not "insane" but oooh its weird..

OK, I was logging in the other day and I was entering my password... and for some reason my cursor wasn't in the password box (I think I accidentally touched my mouse pad) and when I hit enter I got the old wrong password message...

So I re-enter it, hit enter and this DOS script box appears with bajillions of lines of code whizzing through it, then my viewer starts up and after my screen does a monitor resizing thingy (no idea what the technical term is) and then when SL eventually starts up its maximised to the extent that I can't see the title bar.

And also when I switch from SL to another app on my lappy it takes ages and goes through that weird monitor resizing nonsense and sometimes crashes.

Any ideas?
Cheers
Metal

overheating?
Mainboard somehow things that it should change the screen resolution?

Thanks Ollj but I fixed it in-world with a helpful guy on Help Island.

I must have accidentally unticked the "run SL as a window" box although I can't think how.

Cheers
Metal