What did I break?
 

So I was moving my computer to a new case today and after I got everything in and booted it up I kept getting errors saying that the graphics card just recovered from a hardware lockdown and now is running in software only. I took the card out and put it back in and now my monitor stops getting a signal after I was using it for about 10 minutes. When it is just sitting there downloading something it can run for hours without a problem.

Could I of messed up my graphics card or my AGP port on my motherboard?

Its possible, but I would guess it might bee dirt from the move, or possibly just loose. Make sure everything is in there good, and dust it out with some canned air. If that doesn't work, try deleting the driver and restarting. The card should reinstall the drive with no problems.