ATI Radeon 1300 512 Mb ram video card

help. Just bought new 22″ LCD monitor. When playing DVDs,the monitor intermittently goes black, then grey, then resumes playback. Also does this in 3D preview in catalyst control centre, Was OK with 19″ LCD .Refresh rate set to 60Hz. Should I instal latest graphics drivers or is this a monitor problem. Resolution 1680×1050. Cyberlink Power DVD 6 now also presents playback problem and closes down prompting me to send error report to MS.
Set up is Asrock 945 Intel chipset MOBO, Core 2 Duo E6603, 2.4GHz processor. Windows XP Pro. 2GB RAM. What should I do?