can't see my router/modem anymore

After a powercut I'm unable to connect any longer. Other computers here can
see the modem and connect, I can see other networks and connect to mine with
a cable, but I can't see my own router/modem wireless. After some initial
problems when installing a new laptop I was able to detect the modem, when
installing other wireless devices it stopped working and I had to enter the
MAC address by hand, but it worked fine then. Now this. I've checked,
reinstalled and reconfigured everything I could imagine and find in manuals
and on the internet. I travel a lot and always have to adapt to changing
network environments. I'm working on a Toshiba Satellite Pro M40X with an
Intel Pro/Wireless 2200BG card and a Speedtouch370 router/modem. Windows XP
professional.