Access to Wireless lan from 802.11g adapter BUT NOT from 802.11badapters

I have resently upgraded my Linksys router BEFW11S4 to a new WRT54GX
Now I'am having trouble getting my 802.11b wireless network adapters to
access the LAN.

I have the following scenario:

1) Two computers connected directly (wire) to the router - everything
here OK (internet access, shared network ressources etc.)

2) One computer with a Netgear 802.11g wireless adapter - everything
here OK (internet access, shared network ressources etc.)

3) One Laptop with Centrino Technology running 802.11b wireless -
internet connection is ok - BUT NO ACCESS to network ressources

4) One laptop running on an USB 802.11b wireless adapter - internet
connection is ok - BUT NO ACCESS to network ressources

I have set up my router to use mixed mode, and several other setting to
ensure compatibility for the old b-standard. But nothing seems to work??

NOTES
If I connect my laptop directly (cabled) to the router - I can access
the network ressources.
I did not have any trouble with my old router with mixing 802.11b and
802.11g.

I have ran out of ideas..... maybe someone can help?

/ Thomas Christensen