Are you able to get into safe mode at all?

http://www.computerhope.com/issues/chsafe.htm#03
Getting into Windows Safe Mode.

http://windows.microsoft.com/en-AU/w...t-is-safe-mode
What is safe mode?

I had a similar problem as you described in the first paragraph but I was running xp pro, not vista.
Turned out to be some sort of major error which was described as a "loop". It beat me unfortunately.

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p.s. you should have bought a mac.

I had similar problems and it was the hard drive failing.
4 years is a long time these days!
Both of mine in the new PC went within 2 years-luckily under warranty.
Take it to a PC repair shop where they may be able to download your files safely, then run some tests.
Mind you, the repair shop said no problems, then next week it crashed, so....
Anyway, prepare for the dreaded crash.

Thanks everyone!

I ran chkdsk and it came up with no problems. I ran startup repair and it came up with no problems. I still don't trust it.

At this point we are logging off of individual accounts and then putting it in sleep mode while we wait for the new power cord and then we shall see if it helps. I am wondering if it's just not getting enough power to start windows. My battery is old too and it has gone past half life of what it used to be.

As long as I don't shut down completely it doesn't seem to have any problems, so sleep it is!
I am getting a portable hard drive this week to back everything up, and hoping it lasts until then!