I get the same message and its really annoying me i've tried multiple ways of fixing Public Liability Insurance but still get the message!!

What ways exactly? Also, this was long ago but I think all you need to do is (re)install the latest patch; if that doesn't work, uninstall and reinstall the game, too. (You could also manually unpack files from the update and place the correct version of the DLL to wherever it belongs.)

Sorry for bumping this thread, but I think I might have a hint with this, and I think I might have stumbled into this one...

Did you, by any chance, install Resurrection of Evil before patching to v1.3? I'm starting to believe that installing this addon before installing other mods, such as Classic Doom, might just be the culprit. I'm starting to wonder if this would have anything to do with it. Perhaps reinstalling and patching Doom 3 by itself without adding Resurrection of Evil to it might work. Let's see if that would solve any problems.

Change the dll with another similiar..Please look for it at google, but download it manually from a dll's site

https://www.google.com.mx/#q=dlls

check there please