Continuous reboot after adding a/c power

[tomfax]

Subject: Dell d430 laptop power issue: the pc operates fine on battery power. However, when I use AC power, the pc goes into an auto reboot loop and will continue doing so indefinitely. running win XP sp3. I also sometimes experience an auto reboot when addining a USB device.

Is this a hardware or software problem? how can I diagnose? I have run all the diagnostics that came with the dell d430, and they all say that everything is running fine.

I am new to this, so my apologies in advance as I have probably not anticipated some of the information that will be needed.

 

[soundguruman]

Your operating system most likely corrupted, and can be repaired using the instructions posted in this forum, sixth post from the top.
I think that if you do the repair, the problem will stop.