It doesn't work!
Ok bloke, here's the thing...changing the aidefault file as described above (and in the file itself) DOES WORK.
I've got 4 installs of BF2 (incl. AIX, FH2, POE2, and PR mods) on two PC's, both running XPSP3. This method of modifying bot numbers/difficulty works on EVERY mod I've got.
If you changed your aidefault file as suggested, it should work. If it doesn't, then I'd say the problem lies elsewhere.
Providing a few more details might shed some light on the problem, dude.
Make sure the document is write protected...
Yeah, I've heard that too, but mine aren't write-protected and I've never had a problem.