How to troubleshoot problems sharing internet connection via WiFi on OS X

I am at a hotel, plugged into their network via Ethernet on my MacBook. I want to share the connection via WiFi to two other computers. I went to Prefs > Sharing and set up internet sharing. I know it's working because my friend with a Mac can access the net. My friend with the PC can see the network, but can't connect to it. In the sharing prefs, airport options, I chose these options:

Channel: Automatic
Enable encryption: yes
WEP Key length 40-bit
password length: 5 chars (as specified in the instructional text)

Update: I tried it with encryption turned off, and it works. Of course, I'd rather not do that...

Any ideas?

You more than likely need to enter the full WEP key rather than whatever 5 characters you've chosen for a password.

To clarify using the same example as is given in the linked article: if you typed "apple" into the password field the Mac gave you, you're going to need to enter "6170706C65" on the Windows machine.

A solution that worked for me, hope it works for you too.

I also assigned 13 character password (using characters 0-9 and a-f only) and this did fix my connectivity a few weeks back. However, today, the windows machine, which connects to my mac's 3G internet connection, which is by way of USB Dongle, stopped working again.

I checked to see if I could browse with my iphone, also connected wirelessly. Same problem.

It then occurred to me that I should check the network settings (System preferences/Internet and wireless/Network) to see what was connected to the internet. I noticed that ethernet(en6) was connected to the internet (which must have been my 3G USB dongle) and airport was on but had a self assigned IP address and could not connect to the internet. So I first tried to renew Airports DHCP but still couldn't connect. So I set DHCP manually using self assigned IP address. The IP address for the ethernet(en6) connection that did work was 197.66.215.75 so I used 197.66.215.76 for Airport. This confirmed that airport was now connected to the internet.

However, same problem, neither iphone, nor win machine could connect to the internet.

I then went back to the internet sharing menu and played around with "share your internet connection from" in my case it was ethernet(en6). I changed it to airport and tried to connect but same problem, no connection. After cycling through the various connections I could share from, I went back to Ethenet(en6)

Oddly enough this fixed the connection problem and now iphone and winmachine can connect to the internet again.