Battery won't charge while the computer is running, but will charge when it is turned off

I've never seen this happen before with any laptop, and it wasn't true of this one until earlier this week. The battery will NOT charge while I use the computer, BUT, if I shutdown, the battery will charge just fine. Up until 1 week ago the battery would recharge while I was working on the computer and the AC plugged in, now, the only way to charge the battery is to plug it into the AC while the computer is turned off.

I have noticed that it will not charge in standby mode either, off means either shutdown or Hibernating.

I can't find a battery option in the BIOS and I can't find any switch inside windows to inhibit battery charging.

What do I do to fix this problem.

The battery life is no longer what it used to be, it only lasts about 1:15 when fully charged, but that is quite often enough, however this not charging makes it hard to get an 1:15 of use since the battery starts at the point it was the last time I turned it off.

Mark Jones