D-Link DSL-604+ and DWL-650+ Problems

I am trying to help a family member of mine. They have got a D-Link DSL-604+
with one PC connected via patch cable. There are 2 laptops with a DWL-650+
PCMCIA card in each.

One laptop is fine, but the other keeps disconnecting from the wireless
network every few minutes or so. The DSL-604+ is using the latest firmware,
but the problem remains. I don't know where the problem lies because the
D-Link utility reports that the signal quality is between 90 and 100%, and
the signal strength around the same. The utility always shows 3 out of 4
bars signal strength in the task bar too. I have tried uninstalling the card
and reinstalling it, but still the disconnection problem remains.

Any ideas? Many thanks in advance.


--
Sebby