Those look like rendering artifacts and would indicate that its possible video card failure. I can't seem to confirm, but typically dell systems have a onboard graphics adaptor, and on a core 2 era machine, these are disabled when the discrete card is in place. If you have a VGA connector on the motherboard, even a capped one, you can try removing the discrete card to check if this still happens.
From what I'm seeing I was incorrect about my guess that this has a discrete graphics out - this is a slightly oddball system that uses a BTX form factor, and kills off most of the legacy ports. In this case you may need another graphics card to test - the XPS 410 is an identical model with slightly different base specs and lack these.