Unable to add the interface (...) to the Router Manager for the IP Protocol - error on Win XP computer

I have a WinXP Dell 8300, which is new, with a Microsoft USB wireless adapter that connects to a Microsoft wireless 802.11b router. The MS wireless router is connected to a DSL modem. I also have two other Win98 machines - one a Dell R450 running 98 and the other an IBM Notebook running 98/SE. Both of these machines have PCMCIA wireless adapters to connect to the WiFi network and access the network.

I frequently find that my Dell XP machine hangs, and needs to be rebooted. When I look at the events viewer, under system, I keep finding the same error message -

This is listed as error 20106, but I cannot find any information about it on either the Dell website or the Microsoft website, or through Google, that tells me what to do.

BTW while I do have both Clients for MS Network and File/Printer sharing enabled on all three computers, I have also checked and a) workgroup names are the same and b) DHCP is enabled on all computers.

Any advice or suggestions would be most appreciated.