If You are using AMX 2006.x version You shouldn't have all its modules listed in metamod's plugins.ini. If You are using any older version of AMX - everything may happen. You can use the
All-In-One package which includes AMX X 1.76d, pb mm V3B18c and metamod 1.19 - it contains everything You need. AMX X is a similar project to AMX (they both have the same origin), but AMX X is still supported and developped - AMX is not.
The installation of All-In-One is easy - You need to download the zip file, then uznip all the crap into the main "cstrike" (or "czero" - depanding on the mod You are playing) folder - let overwrite all files. This combination is tested and it doesn't crash (excpet You want to use it under old CS1.5 - then You need to make more effort to get it working).