Anyone know how to disable the "Web Page unavailable" popup?

I was wondering if anybody knows how to disable that irritating "Web page unavailable while offline" popup that internet explorer puts out while in Work Offline mode, the one with the "connect" and "stay offline" buttons.

My situation is, I'm pretty sure I've got that background downloader "iexplore.exe" virus but can't get rid of it. I've tried most of the fixes that I can, but it seems to be invisible to all the free antivirus and anti-spyware stuff I can get, so I'm trying to just ignore it. Setting Internet Explorer to Work Offline mode seems to block it, at least (can't steal my info if I don't let it online, haha!) but it keeps trying to connect about once a minute.

Since internet explorer puts out this annoying popup everytime a program tries to connect but can't, it pops up about every minute, always in front of all my other windows and always in the dead center of the screen. I'll usually just click Stay Offline or the upper-right X, but that only gets rid of it until the next time it tries to go online.

I know I probably ought to try to get rid of the trojan/worm/whatever, but I've been trying to do that for days and it seems immune or invisible to all the free programs I have access to. I'm really not very good with computers so I'm a little wary to try any more in-depth and complicated attempts to fix it, and I think it'd be much easier to just let it keep impotently trying to connect and blocking it, if only I could make this irritating Internet Explorer popup go away. Anyone know how to do that? I'm okay with it continually trying and failing to connect, I just don't want to hear about it anymore.

I'm running windows XP and IE6, I think. The browser I actually use is Firefox, so I'm okay with gimping Internet Explorer into complete uselessness if necessary, just so long as it's still my default browser (if I switch the default browser to Firefox, I assume it'll start trying to connect through that.)

Thanks in advance for the help. And er, if possible, pretend you're explaining it to a child. D: