Internet Sharing Problem Tiger to Leopard

Hi,

I searched the forums but didn't find this particular problem. Please redirect me if this belongs somewhere else, or if it's been dealt with where I didn't look. Thanks.

I had this working before, but for some reason it's stopped. I have a MacBook (1 year old) running Leopard. I had been connecting to the internet using my iMac's ethernet connection (i.e. I use the Leopard AirPort to connect to the iMac's ethernet connection). For what it's worth, I'm using AT&T Wimaxx--which worked before--and was told by their techs that it wasn't proibited. Does anyone have any idea what may be going wrong?

On iMac (10.4.11): Under Apple > System Prefs. > Sharing > Services I only have Personal Web Sharing checked. Under Under Apple > System Prefs. > Sharing > Internet I have "Internet Sharing On: Sharing your Built-in Ethernet connection... To computers using AirPort". Oh, and the AirPort is on.

On MacBook (10.5.6): Under Apple > System Prefs. > Network the status of my AirPort is 'On" thought it says AirPort has self-assigned Ip address and may not be able to connect to the Internent. Under Apple > System Prefs. > Sharing there's nothing checked. The AirPort icon in the menu bar shows a strong connection (the computers are right next to each other), only Mail won't take accounts online and no browsers (Safari, Firefox & Opera) will load any pages (I've tried various different URLs).

I'm not running and virus software on the MacBook. The iMac has Norton, but it's also never been a problem before.

Anyway, I hope this makes sense. Please let me know if there's Not Enough Info. Many thanks.

Come on. No one has anything to offer on this?

I really can't believe that no one else has had even a similar problem. I realize there's probably a very simple solution to this problem, but I'm at my wit's end.

seriously!?

no one??