Laptop goes hibernate at 100% full battery when A/C cable is out

[ironcrush]

My Toshiba laptop which worked fine with other version of ubuntu and is still working fine on Windows, started giving me trouble with battery issue. I cannot use it without AC cable plugged in. As soon as I disconnect the AC cable(main power) it goes straight in hibernating mood even though battery shows 100% full.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: acpi 1.5-3ubuntu1
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic i686
NonfreeKernelModules: nvidia
ApportVersion: 1.23-0ubuntu3
Architecture: i386
Date: Tue Oct 25 09:14:32 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
ProcEnviron:
 LANGUAGE=en_IE:en
 PATH=(custom, no user)
 LANG=en_IE.UTF-8
 SHELL=/bin/bash
SourcePackage: acpi
UpgradeStatus: No upgrade log present (probably fresh install)