slow or no internet connection w Airport

[lupus46]

Hey,

Two days ago, my Airport on my first gen MacBook has been having trouble connecting to the internet. The signal is relatively strong (three-quarters of the bars are full) and I've eliminated the possibility that my wireless router is to blame - other computers pick up the signal and connected to the internet fine with it.

When i initially turn on the computer, I'll get an internet connection via airport for about a split second and then it will either slow down dramatically or be eliminated entirely (while still showing a strong WIFI signal on the toolbar). When I turn Airport off and plug into the web via an ethernet cable, I can connect to the web fine and at normal speeds.

I've tried to find ways to diagnose the problem and find a solution but with no luck. Can you help me out?

Cheers,

alex