open notepad (goto start -> run, type in
notepad press enter) type in
Code:
win32 addons/amxx/dlls/amxx_mm.dll
and save it to "$gamedir/addons/metamod/plugins.ini"
make sure you use quotes when you save.
I cannot attach a .ini, I will attach a zip, just in case, I would recommend doing it the above way though, just so you do it on your own.