HDTV as monitor

I have a Relisys RLT32AG20 32 inch LCD TV which I’ve been using with a spare pc I had to browse the net from the comfort of my armchair. Its been working fine for a few months (at 1024×768) but recently the picture from the pc won’t centre properly, I’ve tried reseting everything, re-installing drivers etc but it doesn’t want to re-centre. The graphics card I’m using is an ATI Radeon 9200se 128mb (yeah I know its feeble but it was a spare) any ideas as to what else I can do?

Thanks Simon