1) Borrow a PC laptop.Can you outline the steps I need to take to troubleshoot the sleeping function?
2) Install PSUmoni on the laptop
3) Connect the laptop to the P2140
4) Watch the PSUmoni indicators while you Mac is mis-behaving...
Seriously, we can guess, speculate, and tweak for hours, but the PSUmoni will tell us in seconds what is going on. My guess is that your low battery threshold is set too low.
BTW... I just noticed your post topic..... very clever!