thistlechaser | No dying, computer

This morning someone linked me to an image, and I noticed that it had a really odd background (the area of the window outside of the image itself, but within Firefox's view area).

Today I took a screenshot for someone else, uploaded it, and noticed the "blank"/black part outside the screenshot looked very odd in the same way. See: Strange background.

The image in the middle looks just as it should, but the screen to either side of it should be plain black.

Happens in IE and Firefox both, happens on both monitors (hooked up to the same computer).

Darned laptop is only two years old. Looking on the Amazon page I bought it from, the only warranty I see mentioned is "This laptop is backed by a 1-year limited hardware warranty.", so that does me no good.

It has been running hot lately, even though I blew the dust out of it last night or the night before. I don't know which number "counts", but these are the readings I get from my monitor at this moment:

GPU: 76C
HD0: 50C
Core0: 95C
Core1: 86C
(Edit: After rebooting, with no MMO running, the temps are 45C, 53C, 60C, 30C respectively.)

I have no idea how there could there be a 45 degree difference in temperature within a laptop...

How much trouble am I in? I know nothing about hardware. :/

Edit 2: Rebooting seems to have fixed the issue. Would this kind of thing come and go?