Can't connect to any other computers in network once upgraded to 10.5

[stagi]

I used to be able to connect to my laptop (macbook pro) from my powerbook g5 over our network (Apple Airport Extreme) no problem. I upgraded both computers to 10.5 (and now 10.5.2) and ever since the 10.5 upgrade have not been able to connect. I tried screen sharing and just the normal connect as through the finder and nothing is working from either computer.

Should I reboot my Airport (and if so, how do you do that)?
Any other suggestions for me?

Thanks,
Mark