If they're gray or dark gray gray dots aligned in a grid pattern across the screen, you may be on the verge of an e-74 heating issue with your HANA or ANA (depending on what mobo you have) scaler chip. if that chip overheats and starts pulling off the mobo, you will see dots across the screen before it e-74's on you. Try using a heatgun at 400 degrees celcius and move around the chip for 20 seconds. just google images HANA chip to find it on the mobo. if that fixes your video problems then you're xbox is having some heating issues
i have to agree its early e74......
if it was still in warrenty i'd leave it runnning for a week lol so it gets e74 then send it to m$
but if not try adding heat sinks to the hana /ana or the heat gun trick (that didnt work for me.
also there is the over heat it and put som weight on it.....
then let it cool. i found this to worked for a while but after a few days of light use it did it again... and again and again and then went e74 and got kick across my room....
lol