ok, this part:
Code:
ON *:EXIT { 
 if ($group == #exit enable) {  } 
else {    ($group == #exit disable)  }
}

won't do anything, you don't have the comands, and you need to make sure you created the identifier $group (and that you aren't confusing with a variable %), and also you need another : after the EXIT.
Code:
 on *:EXIT: { <the command to disable the group> }


and about the second part,
Code:
 ON *:EXIT {  
if ($group == #pmask enable) {  }  
else {    
($group == #pmask disable | splay disconnect.wav | copy $mircdir/mirc.ini D:\ )  }
}


in this part you also need the : after EXIT, and again you use if but you don't have the commands to cancel the group in the { } also you don't need to put the commands in the else { } in parenthesis.