There could be a lot of things not set right, both in your router and the offending laptop, this is all complicated by the fact that the SMC firmware seems to be really hosed. What version do you have loaded in the router, 0.20a (Aug 24 2007 13:38:33)?
I have this and I am having a hard time getting the router to see mac ids of others connecting...sometimes it does, sometimes not...
