Monitor turns on after windows starts.

When turning on my computer my acer p244w monitor does not turn on until windows vista64 bit has booted up. Thus no allowing my to enter my bios. Can anyone tell my why this is?

All drivers are updated. It did not do this when i first put the computer together.

I don't think windows activates the monitor....
I believe it auto senses voltage from the video card, but I'm not sure either.
Can you remember what you did just before it started, like installing new video drivers ?
Try hitting the pause button upon boot-up when you think it's on the bios screen and give it a few moments (monitor) to warm up and see if it catches...