Weird ping behaviour using 3Com OfficeConnect Wireless-G access point

I have two laptops connected to a 3Com OfficeConnect Wireless-G access
point. Both can ping access point, Router and public IP's. But laptop-A
cannot ping laptop-B before B has pinged A. That is, if laptop-A pings
laptop-B it gets "request timed out" until laptop-B starts to ping laptop-A.
Its the same the other way around.

My setup is a router (Zyxel) connected by wire to the access point (3Com)
and two laptops (IBM and Dell) connected wireless.

Any help would be greatly appreciated as I'm all out of ideas.

Thanks in advance
Martin