Cannot connect my home PC to my wireless router

Hello,

I have just finished installing and configuring my LinkSys WRT54GL router at home.

I have no problem connecting with My laptop to the wireless network.

However I also have a desktop PC with a, TP-LINK TL-WN550G, PCI wireless adapter.
When I do a network scan on this PC I see my Wireless network, meaning that the network card detected the broadcast, however the strength of the signal is 0. Even if I place the router adjacent to the PC.

Please advise
Thanks
Boaz