XP Wireless Connection Requires XP Firewall to be Turned Off

Have an HP LAatop running XP. Home network, using a US Robotics USR5461 wireless router. For some reason my laptop will not connect in wireless mode unless I turn off the firewall on the laptop. Once the laptop is connected I can turn the firewall back on and everything works fine. What am I missing? I know I shouldn’t have to turn off my firewall to do this.

Thanks,
Bill