Laptop acting wierd when I plug in AC Adapter

[makeitcount]

When I plug in the AC adapter my x40 will make the sound that it's connected, the screen will light up and the battery will switch to AC power and charge for like 5 secs, then it will dim down back to battery light, and begin using battery again.

What causes this? I've tried using a different ac adapter and then it will charge fine and just use power from the ac adapter. So is this just a faulty adapter?

Also I've been unable to find either of the FRU's on the adpaters, are they even valid (they look genuine!)

FRu P/N 08K8211
FRU P/N 93P5016

Thanks

[ryengineer]

That's (08K8211) a valid FRU part number.