Mac Connecting to Linksys WRT54G

I have an strange issue that I need to bounce off some people. I recently sen up a wireless network for my father at his house using a Linksys WRT54G and a DSL modem. I set up his new network fine. His PC connects fine via Ethernet. My freind's Mac Book connects fine. My Mac Book Pro is having a hard time. As a little background, at my home I have the same router and it works fine. I have connected everywhere else with no problem.

I am having two problems and they must be related. First, my Mac sees my fathers network, but when I try to connect I get an error trying to connect. If I select "other" and put in his network name and WEP128-bit encryption key, it connects fine. Then when I select any internet application, it times out. I checked the network preferences and it does not appear that I am getting an IP address (it is set to DHCP and works everywhere else that I connect to). If I manually change the IP address and router setting it connects to the Internet and all is fine. As soon as the Mac Book Pro wakes up from sleep (or reboots) I have to reenter the encryption key (and it gets tedious). My Mac works everywhere else, my dad's router seems to be working, but the two don't work well together (tho I can force it to work).

Any ideas? Thanks in advance for any help.