Slow game after installing NETGEAR WAP ME102

Hi

I have a Broadband(DSL) cable modem (SB4100) that connects to an SMC 7004BR
Broadband Router. From the router I connect to a CentreCom RH505BE hub that
allows me to then connect via BNC to another PC in a different room. All is
fine and no problem with speed.

I have just bought a Netgear ME102 WAP and connected it to the 7004BR.
After some set up I connected the WAP to my laptop and again have no
problems with speed.

My son plays a network PC game (World of Warcraft) on the PC connected via
BNC and has had no problems until I switch on the ME102 and then his game
starts running very slowly.

I can't understand why having the ME102 active in the network but with no
active connections (laptop is now switched off) is causing such a slow down.
I haven't noticed anything on another PC connected to the 7004BR via RJ45
but admittedly I am only using this PC for surfing the net.

I have set up WEP on the ME102 (64 Bit).

Can anyone explain why having the WAP on but not being used is causing this
problem.

TIA

Steve