UltraBay Battery not charging anymore

[Mad Phil]

Hello, I only submit my problem to know if any of you already encountered this behaviour:

We recently had several of our users reporting that our R52 didn't charge till 100%. It appeared that the Ultrabay battery didn't charge anymore!
But every time we took the Ultrabay OR the PC to our helpdesk, the R52 charged again till 100%.

So we tried to reproduce the problem and found this:

If the R52 had an USB Mouse and an USB Keyboard attached to it, and was connected to an 802.11a (no problem in B/G) Wireless network, Batteries were stucked at 75%...

Got to make a call... or is there a known solution ?

[sorry for my bad english]