Macbook Internet problem

I apologize for not posting as much as I wanted in the past couple of days. You see, I’ve just been hit back Karmic-style because of this new site I lovingly titled “Mac Complainer.” I’ve been a totally satisfied Apple customer since I purchased my white Macbook back in September of 2007. There’s not one problem. It boots up fast and non-native Windows applications like Microsoft Office and WMV, which I needed, work fine with minor Finder delays. Then I put up this site and a week later I am having an intermittent connection problem. I cannot figure it out, my provider cannot figure it out.

Is this an instance of Mac Karma? I’ll be glad if you can lend any help. First I’ll describe my problem with as much detail as I can.

1. Boot up MacBook. Airport is on. I plug in LAN cable. Internet works fine. Then suddenly pages stop downloading. I ping. No response. I unplug LAN. Airport signal is full bars. Nothing. I reboot MacBook. Internet comes back but stops after a minute or so. Sometimes select pages load but not others.

2. I notice that when Magsafe isn’t plugged in my Internet works fine for long periods. But this is not a sure thing.

3. I also noticed than when I’m not connected via LAN cable, it works fine for long periods again. But, again, this is not a sure thing.

4. Hardware seems fine. I tried using a weak WiFi signal from a router nearby. It works, even when there is only one bar.

5. Must be a router problem, then. But I tried connecting my PC laptop (I’m using it now to post this) but no problem whatsoever.

6. I’ve already tried reinstalling Tiger. It’s not a fresh install, though. Same problem.