Problem with dual monitors

I just got a new computer a month ago (Dell Inspiron 530) with XP Pro SP3 already pre installed, but I decided to try out Vista and I'm liking it. I had already been using a ViewSonic VX1940W and the Dell SE178WFP came with the computer. I tried the dual monitor setup with the ATI Radeon HD 3450, and it's been kinda screwy lately. Every time I turn my primary monitor (ViewSonic) on, the secondary monitor's settings reset and the position is not set the way I want it. My monitors also flicker every hour or so, anda message appears saying "Display driver has stopped responding and has recovered." Sometimes when this happens, I get the bsod.