monitor screen goes black

[stilljetter]

Hi everyone,
I'm new to this forum so please bear with me. I have Vista home premium and when I leave the computer for about 30 minutes and come back the screen on my monitor is black and I can't get a normal screen back. I push enter, esc., etc. .....nothing . I have to shut off power to my system and reboot. Anyone have ideas on how I can correct this problem.

[Robbie]

Have you tried reviewing your power saving settings ie what your computer will do after a set period of time, sleep, switch off etc