Restart problems

This is my first post and I am not very experienced with Vista. I have had dozens of problems with this machine running Vista but my biggest headache right now is that I have a heck of a time restarting my computer. Sometimes it starts, sometimes it doesn't, sometimes it doesn't start but if I let it sit for a night (or days) it will suddenly restart on its own. Sometimes it starts and runs very loud and then settles, sometimes it runs normally. Once I finally get it running it will be fine and then just go off with no warning. Then I can't get anything to work to shut it off, the only way is to cut power and start over. This time when I did that I am left with a lound running tower and a screen that instructs me to reboot or choose boot drive..........I can't get past this prompt. If I unplug and try again I still end up here. My OS was preloaded so I have to disc to reboot from. Sometimes it doesn't communicate with the monitor however right now it indicates that it is.

None of the F keys give me any results....is there a way to try to reboot without pulling plugs anymore? The computer is about 3 years old.

Thanks,
saarstruck

Hello saarstruck,
Go in to your Bios and see if your hard drive is showing up there.
Is the disk you have a Vista disk, or a recovery disk ?.
If its a Vista disk follow this tutorial.

http://www.vistax64.com/tutorials/91467-startup-repair.html

It could be a number of things causing this, MB, Bios, failing Cmos battery, bad HDD, or just a corrupt system file.
If you have anything overclocked, set it back to default.

Carry out the repair and post your results, good luck.