Whenever i run custom zombie maps (Moon from the UGX map manager and Ubaht in a UGX installer) The moon map whenever i clicked it and run it. It shows the desktop very quickly then shows the WAW screen. After a few seconds it stopped and turned into a black screen. I closed WAW and it shows "FS_BuildOSpath: os path lenght exceeded"   
                                                                                                                                                                                     
          Same happens when i try to play Ubaht it loads halfway and turns into a black screen, i closed the game and shows "FS_BuildOSpath: os path lenght exceeded" Can you guys help me? i really want to these two custom zombie maps.

Where did you get your copy of waw? Is it up to date? And where did you install it?

So i found out why it does this, just to be clear i am using a pirated version. But i found the solution to this problem so my CoD World at War was inside a folder and the folder is inside another folder.

 (Because i was re-installing it so many times)  So i put the CoD World at War folder in my desktop (And also i made it an administrator) and for some reason it worked  (Well i don't know if this works for everyone but that's my solution for my problem)

By the way my CoD World at War folder was like this. (I just drag CoD WaW in my desktop and it fixed it)

Folder/Folder/Folder/Folder/CoD WaW