Can't connect to WEP-secured network

I got a WEP-secured WiFi network in my home, which I normally use for my
desktop machine. Today I tried connect a laptop to this network, but
Windows refused to connect. I remember I had the same problem with
another laptop earlier. Obviously, it's not a problem with the network,
since I'm using it every day.

What happens is this: I check the list of available networks, and find
my 'GL' network. I connect, and Windows asks me for the WEP key. I type
it, and wait for 1 minute while Windows tries to connect. Then the
dialogue disappears without any message, and I'm still not connected.

I tried to set up the key manually by creating a network in Prefered
networks in Wireless Network Connection Properties. I've check all the
settings there, and they are identical to the desktop computer. What
more can be done?

Gustaf