Did you hear the machine gun noise when you tried the external keyboard? If you don't hear it, and the external keyboard works, then I agree with garmanma. The fact that the laptop may have been dropped is the crucial statement-laptops are tough, but not indestructable.
I asked about Norton for a reason. In January 2006 I noticed a noise that I called the machine gun. Over the course of the next 2 months, I investigated IRQ conflicts, keyboard buffer overruns, switched out my sound card, got a new keyboard, thought my USB hub might have something to do with it-nothing worked to get rid of the sound. Then out of the blue, I get a message from Norton-telling me there was a problem with Norton antivirus (the only thing Norton on my system) and I needed to uninstall and reinstall. So I did un/reinstall Norton. Got it updated. The message came back. I had already decided to get rid of Norton, so this time I installed AVG. Didn't take me long to realize the machine gun had run out of ammo. The only thing I could come up with was an update to Norton caused the issue. An accidental solution that no one ever thought of. That my friend, is why I ask about Norton whenever someone mentions the machine gun. Might not be the cause of your problem, but it could help someone else reading this. I suspect you don't have Norton, but I had to ask.
Edited by Queen-Evie, 20 December 2008 - 12:55 AM.