5.2.1 IDE reboot on untar?

[J.D. Bronson]

I have noticed this twice on 5.2.1 on x86...

I have a 350MB tar file that I do the following on:

# tar -xpf filename.tar

...at some point before the tar is finished, the machine reboots!

I have seen this 2 times...but cannot always duplicate this. there is 
nothing on the console or in console.log when this happens. It is like 
someone hit the reset button and then the machine comes back up and fsck's.

Is this a known issue?

  -JDB