I have a rather old Sony Vaio (VGN-B1XP) it worked fine for a long (and sometimes roufgh) time. Now it suddenly does not detect anymore that it is working on batteries (i.e. windows XP is always stating in the taskbar that the charger is connected). The problem is that the operating system will NOT check the battery level and when working on battery the system stops without any warning.
Any suggestions (PS I did not install recently any software or modifiy the system, as far as I remember and aware of)