Thanks, Curt - I didn't consider it a firewall or pop up blocker issue. The banners appear under the names of the sponsors. There are also individual forums for sponsors. You can find them towards the bottom of the forums list.
It's not a popup blocker, but a banner blocker. If you want them to show properly to everyone, it's advisable that you resize the banners, even making it one pixel larger or smaller then standard banner sizes will allow them to show.
Also providing a link on the text is a good idea for those who can't see the banners. It makes the site more efficient.
The banner sizes are typical banner sizes. If people have banner software installed, then they are basically saying they don't want to see ads. If it is the size of the banner that does it with these software packages, then I guess it is working
We don't plan on changing the banner sizes just to fool people's software packages on their computers, I certainly know I don't like it done to me
I certainly will considering adding a link to the text names at some point though.