Add .PHP File as Plug-in - Admin Panel Will NOT Start

[ae3799t]

I do hope this is the right forum and apologize if not. I thought this might be one of those things that takes some programming knowledge, as well as an understanding of the forum itself. We have VB 4.2

One of our guys wrote a .PHP file to rotate banners, then he tried to add it to the Admin Panel as a Plug-in. Now when you try to log-on to the Admin Panel you get the following error message.

save from other path!Unable to add cookies, header already sent.
File: /home/roadtr5/public_html/forum/global.php(29) : eval()'d code
Line: 16

Does anyone understand this enough to figure out what happened from my description?
The forum is still up and you can look at things, but you cannot edit a thread and the sign-on page of the Admin Panel comes up to log-on, but when you do, you get a blank page with the above error.

Since the Admin Panel is hosed, you cannot edit the forum either, so we are basically down.

Any help would be greatly appreciated. I can only guess that one of the templates used for plugins was damaged, but even if I knew which one, I could not get to it by way of the Admin panel.