Laptop Dell 9100 problems

Hello, I have a Dell Inspiron 9100 laptop with a P4 3.2 ghz processor,
1 GB or ram and a Radeon 9700 mobility graphics card. This laptop is
experiencing problems.

I was working on it once, and went to take a 10 minute brake. When I
came back, the laptop did not respond. It just displayed a static
image on the screen of whatever it was doing before I left. None of
the buttons worked, but the image still displayed on the screen. I
let it sit there for 5 minutes hoping that it might clear up and then
I turned it off by holding down the power button.

I let it rest for 5 minutes and tried to turn it back on again. It
starded with the POST test, but halfway through it it just hung
again. Again there was no response from any of the buttons, and the
laptop produced no beeps. The fans were still blowing and the image
just displayed there with the POST bar stuck about half way through.

I tried restarting it several times, and every time the same thing
happened, just with the POST getting stuck at various points.

The next day, post completed successfully, and I was able to get to
the BIOS. Then it hung again when I tried to go to the next page in
the bios, and it produced some random characters along with the normal
text that was supposed to be there. (very strange)

Today I was able to get the laptop running and I was able to boot into
windows xp. The computer hung after about 15 minutes of normal work.

These are strange symptoms, and it is a fairly expensive computer that
I want to get fixed.

Here are some of the questions: Has anybody ever experienced similar
problems here, and does anybody know of any solutions? This has
completely stomped me, and I have no idea of what might be
malfunctioning or what might be going on.
Can anybody also please give any suggestion in how I might be going
about trying to trouble shoot this, before I will send this machine in
to make repairs.

I am fairly computer technical and have no problem with taking the
laptop apart, so any suggestions would be welcome.

I have also posted this in the laptop discussion group.

Thank you!