Banner sidebox image is invisible

Zen 1.3.8
None of my sidebox banners are visible. I have installed them per ZenCart instructions, tried both Firefox and Explorer, I even uploaded the Zen Cart 1.3.9 on my localhost server and they are still invisible. The link is there but not the picture. Can someone please give me some idea how to make the banners work?

http://writerscramp.us/cubby/index.php

Thanks

Could you explain exactly what you mean by 'sidebox banners'?

I'm seeing both bannerbox and bannerbox2 on your site, both with headers and content.

If you're referring to different boxes, you may need to take your site off Down for Maintenance.

With a little help from my friends, I have determined that everyone can see the graphics except those computers on my Local Wireless Network. Rebooting everything didnt help and the Linksys hub is fairly new. Does anyone have any idea as to what could be wrong?