More likely there is a hard drive glitch - cold solder joint, bad cable, etc

I don't think so... it doesn't happen on AC, and the consistent time interval (nine and a fraction minutes every time, whether the unit is warmed up or not) would argue against any sort of random, intermittant failiure like a bad solder joint on the IDE header.

Remember the "jiffies" problem of a few years back? That seemed to be a hardware problem but was really software. That problem was fixed in 2.0b13 but this problem seems to be of a similar nature.

tanstaafl.