[KWo]

Check the date of metamod's creation (date creation of the file metamod.dll). Make sure You are trying to use the latest one. If it's 2005.08.23 or 2005.08.29 - it's OK. Make sure Your CS works correctly without metamod. To check this - replace that line in launch options:
-dll "\addons\metamod\dlls\metamod.dll"
by
-dll "dlls\mp.dll"
and try to startup the game. If it doesn't want to work - it menas it's not metamod problem, but Your CS instalation.
NOTE:
If You are using non-steam CS1.6 or non-steam CZERO - we don't support them.

[EDIT]
Are You sure You are playing CS1.5 on Steam? No-one here tryied old CS1.5 with STeam - so it may not work with latest metamod correctly. I know this - the latest metamod doesn't work correctly with old HL CS1.5 (it works only on dedicated server, but doesn't on listen server), but I don't know if it works with CS1.5 based on Steam. For sure - it works with Steam CS1.6 and Steam CZERO.
[/EDIT]