Why does Game resolution switch to 640x480?

[DayTradeSniper]

Have an new HP and when I start any games the game resolution switches from the normal 1280x1024 to an obnoxiously huge 640x480! I checked the game resolution settings and they are also at high settings...usually 1024x768... Installed a new PCI card still same results. I am at a loss to what causes this? What am I Missing?? Thanks