Go to the file cstrike\addons\amx\config\plugins.ini
and find these strings:
nextmap.amx ; displays next map in mapcycle
timeleft.amx ; displays time left on map
and comment them out by semicolon. I mEAn (

) so:
;nextmap.amx ; displays next map in mapcycle
;timeleft.amx ; displays time left on map
It should also prevent to overwrite the results of the commands like nextamp and timeleft...