AVR-Chat

> From: David VanHorn
> ....
> Most likely, something is writing that bit.
> I've never seen the ADC in any AVR just take off on it's own.
> Check your source for writes to that address, both in I/O and SRAM space.
> ....

Problem was caused by going into sleep mode (sleep mode = Idle) while ADEN
was set.  As I later found described in the data sheet this (also) causes a
conversion to start (noise reduction mode).
 
Cheers,

Chuck Hackett
"Good judgment comes from experience, experience comes from bad judgment"
7.5" gauge Union Pacific Northern (4-8-4) 844
http://www.whitetrout.net/Chuck