Well, your answers change things a bit. My computer doesn't munge things properly unless the batch files are edited, so I thought that was the issue, but according to your answers, this is not the problem.

When I munged your map straight from the .rar file, it worked fine on my computer. You can try the fix I used for my computer found HERE, but this is almost assuredly NOT the problem and will neither help nor harm your computer in any way.

The only thing I can think of is that for some reason an update to your computer or a new program is interfering with the process of running the map, though I don't know how because its not
1. the addme.script
2. improper file moving (as per Rep's suggestion)
3. bad munge files (my check)
The only way that I can think to fix this would be to restore your computer to a time before the munged maps stopped working.

Thanks for your help. I'll try to restore my PC back to the original condition and report back.

EDIT:
Is there a way to find out when a given programme was installed? I was trying to find it, but couldn't.

I forget what the category is called on XP, but I think it's "Add and Remove Programs" under the control panel. If you go there, it should have an install date for each program.

Yeah, I checked there, but I couldn't find the install date. I'm having some ideas though, so I might have this working soon.

EDIT
Sorry about the double post, but I fixed it. I know - the reason is so pathetic that you would;ve thought I should've thought of it straight away. Sorry! It was the addon folder. I renamed the addon folder to addonsss, then made a new folder called addon, copied the maps across, and everything works again. I'm so happy!
Thanks for all your help regardless, though.

This can be locked now! Thanks again!