BleepingComputer.com: laptop battery help

I have a Dell Inspiron 1501 laptop that I bought new about a year ago.

I have a problem with the battery. When I unplug it from the power source, within 5 minutes, my low battery indicator is blinking red. However, when I hover over the battery icon with my mouse, it still says there is about 2 hours left. Within 5 minutes, it acts like my batter is low, so it shuts down to standby mode until I plug in the power source.
Note: Sometimes, when I plug my laptop to the power source, I get a message saying that my power source cannot be recognized. I usually just ignore the message because it still keeps my laptop charged anyways.

Any help would be appreciated. Thanks.