Okay, so there's a single wireless network that my laptop has troubles with. My Macbook Pro used to be fine with it until it changed to using channel 13 (or 11?). Since then, after being connected to it for a while it disappears from my laptop's view. Other networks are showing up fine and other computers (including several Macs) have no troubles connecting to this network. If I clear my system cache using Onyx and then restart (sometimes a couple times) my laptop can see and connect to it again. But it seems that if I disconnect and try reconnecting I have to clear my cache again.
One thing to note is that if I put my computer to sleep while connected to this network it has no problems reconnecting on wake up.
I've got a 15" Macbook Pro 2,2 with Leopard 10.5.8.