Commands which call exec() or shell_exec() ??

Hi -- - Strange problem. One of my applications was just moved to a new server. The new server has php configured to blacklist some functions (using "disable_functions="). One of the "banned" functions is exec(). The error log is reporting "shell_exec() has been disabled for security reasons" --- but exec() or shell_exec() are not in my code *anywhere*. The program and line number being reported makes absolutely no sense. Are there other php commands that really call exec() or shell_exec() ??? Any clues how this could happen? Fixes (other than un-blacklisting the command, of course)? Many thanks, Ken