I have been reading these forums for the whole weekend about the shutdown problem with the Acer Aspire One AOA150.
Tried all the solutions, including taking the netbook apart, and nothing worked.
FINALLY I GOT THE SOLUTION THAT WORKED FOR ME!!!! :-)
Basically it is the CPU overheating. I think whatever controls when the cooling fan switches on does not do its job with the latest BIOS update (Which IS needed to get the battery to charge).
I installed: Acer Aspire One (AA1) Fan Control for Windows XP/Vista.
Monitor the CPU temperature and set accordingly.
Hope this will save others the time I had to spend on it