Does laptop overheating depend on the battery

Hello,

I've got a ASUS PRO66IC running Windows 7 64bit with all updates installed and I recently came across a strange problem with it. I rarely use it in battery mode since I'm usually close to a power source, but the other day i had to use it on the go and this is when my problem occured.

When the battery percentage (as indicated by the battery meter in windows) reached 35% it shutdown without warning. I tried to turn it back on several times but it would shutdown during start up (just as it would if there was no power left in the battery). When I got back home i connected the charger and the computer powered up just as usual, and the battery (still reading 35%) started charging just as normal.

I've been able to reproduce the problem several times since this initially happened, and its the same thing every time, it shuts down without any type of warning as soon as it hits 35%. At first I thought it was some form of battery reading failure, and that my battery actually was out of juice, but after further investigation this cant be the case. The laptop is fairly new, and from a full battery to shutdown (at 35%) I only end up getting about 50minutes of battery life (with all battery saving features turned on, lowest screen brightness and CPU speed etc, and usage kept to a minimum).

I've gone thru the event logs in hope of finding some sort of clue to what is causing the problem and noticed 5 "failures" of the ACPI, which i beleive deals with the battery, the event-id of this failure is 13. None of these failures have occured when I've experienced the problem, but I figured they might be related anyways.

The computer works just fine when plugged in to a charger and I havn't been experiencing any other problems, the "critical battery level" (and automated shutdown) is set to 5% and shouldn't have anything to do with the problem.

I havn't installed any strange software (infact, I havnt installed anything at all other than windows updates) or changed any settings since the time it was working fine.

Also, if anyone have a similair laptop, is your battery life as bad as mine? I get around 1min/1% of battery with maximum possible power saving (no wifi, lowest screen brightness, lowest CPU speed etc.)

I would greatly appreciate any help that could lead me to the cause of this problem, thanks!