Did you go to the Unofficial 2142 Editor?
http://bfeditor.org/forums/index.php?ac … entry55806
If you didn't thats what would guess to be the problem as BF2 Editor DOES NOT natively work for BF 2142.
Download Part 1 provided in the above link then make a back up file of the ENTIRE BF2142 directory and copy it to desktop, note that this isn't required but I highly suggest it so you can modify BF2142 & FS without worrying about PB booting you for a different version.
Then what I did was extract the files in Part One and place all of them into the copy BF2142 directory on the desktop. Make sure you allow it to replace all files it asks you to replace or this will be pointless.
Now follow the rest of the instruction given in the link above. Note that you do not need to download part 2 if you do not want to edit the original BF2142 levels.
Once you are done, open your copy BF2142 folder and look for an application called BF2editor *its a bulldozer icon* and it should initialize.
Remember you wont be able to use any FS objects if you don't follow TY's instrutions in his sticky.
Beware, Vista will cause the BF2editor to crash if it warns you with a "security warning" (generally asking you to allow an EXE program) so save often. I've lost a good deal to that.
EDIT: After leaving my comp with my map saving I come back to find that BF2editor had crashed. This is a normal thing for me so I didn't think much of it, but when I went to run it again it mentioned not being able to find the file you were having problems with. It told me to reinstall to fix it. I tried to start it up a second time, no luck, but the third time it started up as normal... odd. Just putting this out there as a reminder incase your problems are something I'm missing.