Acer monitor does not get signal every time

If anything try updating the video card drivers. That's what it sounds like, or the monitor is going. The next time the monitor fails to start, just unplug from the input and put back in. If it starts you are looking at a bad power booster on the board. You can also try pluging in another monitor or try that monitor on a different machine. This way you can eliminate which is bad. I had flat panels and crt's go on me and they usually start by this symptom. It shouldn't be the BIOS, if it's been working right along, same with the processor, it either works or doesn't, it's a monitor scenario.