Please help out an aging ThinkPad x31

I have a limited knowledge of computers, well, I know more about hardware than I do about software, but I've never seen this problem before in any of the computers I've owned in the past, so hopefully some people can understand my frustration. I have been struggling with this problem for a week now, and it's driving me nuts (I've never had a problem before with my ThinkPad, very reliable for 3 years... until now). So this is it:

The problem first started out as random programs failing to run, such as the dictionary or image viewer, and the wireless lan refusing to turn off or on. Then I got the lovely Blue Screen of Death. After that, when it restarted, before Windows booted, it'd simply freeze at IBM logo and I found that the hard drive simply was not turning at all. After a couple restarts with the power button, it'd run normally.
So I took advantage of the IBM Rapid Restore program and did the return-to-factory-settings deal, and it was okay for a little bit, then the same problem began to appear more frequently. Sometimes the screen would just freeze, not even the cursor moving (I found that the hard drive just stops turning as soon as screen freezes). Sometimes I get the BSOD and restart without hard drive turning. Sometimes it just restarts on its own.
Here's the weird part I can't wrap my head around: the screen freezes when I remove the battery while the laptop's plugged in. This also happens when I pick up the laptop, or tilt it slightly.
I'm a little convinced that it's a problem with the hard drive at this point, but I've run antivirus programs, system registry programs, and hard drive scan programs, and so far they've detected nothing.

Any help anyone can offer is greatly appreciated. With college starting up again soon, I need to know if I should opt for a new laptop, or if this can be fixed with a hardware replacement.

Thanks in advance!

 

You ran HD Tune?

 

ZaZ: Yes I did. I actually searched the forum and read the tip you gave about HD Tune to someone else having problem with x31 hard drive. It didn't find any error and gave me an OK for health status.

 

You could try re-seating the drive as well as the memory to see if that helps. As an alternative, you could buy a drive somewhere it is easy to return i.e. BestBuy or CircuitCity. That way you can test it to see if it's the problem. If it ain't it's easy to return.