Hard crash

[dmorin at lear.morinfamily.com (Duane Morin)]

So I walk upstairs to the office today and hear what I can best be 
described as a "puttputtputtputtputtputt" noise, very fast, coming out of 
my speakers.  Monitor is in sleep mode, and activity lights are on on the 
main machine.  Does not respond at all to anything (mouse keyboard, reset 
button).  I have to cold cycle power.  I plug back in and it immediately 
goes back to the putputputputputputputput noise coming from the speakers, 
no spin up time or anything.  I'm describing the sound like that to 
differentiate it from any sort of whirring or kerchuny noise that you 
might normally hear from a hard drive.  This is the sort of thing that 
sounds more like an audio CD skipping, if ya know what I'm getting at.

This sound like a major hard drive crash, or something more sinister?  I 
won't really have time to crack everything open until tomorrow so I 
thought I'd throw this out there now in case anybody's got ideas for me to 
try.  I was thinking that if it's just hard drive, then there would at 
leat be a few seconds of bootup time for the BIOS, but I get none of that.  
So now I'm thinking the whole thing is hosed.

Bigger question is what causes such a thing.  I had just put a new power 
supply in it a few months ago because the fan died on me, so I'd be 
surprised if it was as simple as overheating.  The machine had been on for 
a long time (relatively).  As in many weeks.