Strange Behaviour of Wireless Router

Just trying to see if anyone can explain a strange experience I had.

I had a wireless router that we used for 2 laptops. Worked fine till,
suddenly, one laptop would not work. The signal strength was fine,
it could see the network, but would not just work ... even would
not ping and so I am sure that there was no connectivity. However,
the laptop would work at other locations. Even had a 'pro' look at
it at home, but he could not get it work on our router.

Several months later the second laptop did the same. I just got
a new router, and bang ..... both laptops were back to
normal.

I suspect the router for obvious reasons, but what could make it
behave this way?

Just curious ... can always learn something from this kind of
thing, too.

thanks
jg