I have never experienced overheating issue myself. You might want to check the vents etc.   I would also run the extended hard drive diagnostics.
Good Day.  I have a 3 year old Dell Inspiron 1501 that was slowing down so I tried doing a fresh reinstall. I inserted the OS Reinstallation DVD that came with the system (Vista Home Premium 32 bit).  I booted from the DVD, deleted the existing partition (data on c: drive) and let the install DVD do it's thing. It seemed to go through all steps, but when it went to do the first reboot the computer abruptly shut down during the reboot (blank screen and immediately silent). I tried rebooting and while it went a little further into the reboot, it abruptly shut down again. It gets far enough that it appears that Vista has installed, but it crashes during the screen where it says something along the lines of "it's doing it's first install since Vista was installed and needs a few minutes". It just keeps dying before actually booting windows. At this stage, I go back to the beginning and try reinstalling Vista.  Another time it installed Vista and in the first reboot a window pops up advising that Windows shut down before the install could be completed and it instructs you to reinstall.  I'm struggling to understand how the system was functioning before I tried to do the fresh install, and now I can't reinstall the OS. I loaded the Reinstall DVD and even tried to "repair the computer", but no luck.  Any ideas? (Thanks)
Trying to reinstall Vista on Dell - system crashing