Charging problem with my Latitude 100L

I have a Dell Latitude 100L which i bought here in the Philippines and have been using it for almost a year now. The problems I have are the following:

 

1. Laptop appears to be charging but is actually on battery power - here's the scenario: laptop is plugged to an AC outlet and the power icon on the bottom left of WinXP shows a plug which means it's on AC. After about an hour, the power icon suddenly changed to a battery and it informs me that it only has 10% battery power left!! Remember the laptop is STILL plugged to the outlet! This means that all the while, the laptop was on battery power inspite of it being shown as charging. This means that Windows XP is getting the wrong message from the bios or whatever.
 
2. Laptop is on battery power IN SPITE of it being plugged - the scenario: i boot up with the laptop plugged to the outlet. i go into windows and it shows that it's on battery power. I remove the adaptor and insert it again. Still, windows sees it's on battery power. The battery light confirms that it is on battery power. This tells me that the problem is hardware since XP correctly identified that the lapotp is on battery inspite of it being plugged.

 

The problems seem to happen randomly so basically they're hard to recreate. The temperature of the environment that i work in varies from 26-34 degrees celcius (maybe it's the heat?). I can assure that no dust have entered into the machine since my room is clean all the time. My lappie runs on windows XP Home. Bios seems to be updated and all patches to windows have been installed.

 

Anyway, I've returned it to Dell before (here in the Philippines) and their solution was to change the adaptor. I got it back with the new adaptor and after a couple of weeks the problem showed itself again. I returned it again 2 weeks ago and the technicians couldn't recreate/isolate the problem.

 

I suspect that the board may be damaged (particularly the part where it handles power management). It's either that or the battery and/or the actual adaptor socket in the laptop is faulty.

 

Has anyone encountered this before? Anybody from Dell kindly give me some advice...