problem with Team Fortress from Half life

The problem is It runs fine in DIRECT3d but i like opengl better, now i changed mode to opengl and the game runs and plays fine etc… but as soon as game ends and i quit application it turns of my monitor and it goes into orange indicator.

i am running 766 PIII 256meg memory, g-force anhilator pro edition. I have latest DIrect x and have downloaded drivers from creative’s website for the g-force but is creative’s website out of date for drivers i want i end up having to reboot machien because the screen goes blank, is there a way to sort this out?>