hi i think it could be a clash of software as it maybe that you are using windows xp i have had simillar problems with windows xp and eventually found it to be a clash of antivirus software that i was using which was the AVG antivirus and it caused screen coruptions of 4 bit displays 640 480 setting etc
i hope that this may be of some help to you
i hope that this may be of some help to you
