Internet Connection Problems (help a moron)

[oscark]

Ok, I have a netgear wireless card and router with Yahoo DSL. When I turn on my laptop, it connects with my router no problem (good signal strength and link quality). However, for some reason, it won't connect to the internet. Not sure what the problem is though, because whenever I can't connect, my apartment mate has no problem connecting using the same router (although she is connected by ethernet cable). Then eventually, it will just sort of find the internet and connect all of the sudden...sometimes this is 5 minutes after I start up, sometimes 20, etc.

Hopefully I explained this so someone understands, although I have my doubts.

Any advice, please?

Thanks,

Oscar