@retronerd: What brand and model of TV are you using? That might give us some clues... Also, what type of connection are you using between the TV and your PC?
some tv sets are not allowing geometry settings via osd while in rgb av mode. u have to switch to channel 1 , resize the image , switch back to av and check . it can be annoying sometimes .

Tell me about it! I found a Grundig on the side of the road that was like that (CUC 2050 perhaps? Not sure off hand...) and it was a right pain to get the sizing sorted. Had to adjust, save settings, exit service menu, change back to AV, check, repeat, repeat...