Uhh... Try this... I'll explain the problem at the bottom...
NPC Code:
if (playertouchsme) {toweapons Fish}
if (playerchats) {
if (strequals(#c,Fish)) {
this.fon==1;
setplayerprop #c,;
showimg 69,systemf.gif,playerx-1.75,playery-1.5;
showimg 80,@Arial@bc@#s(fishpounds),playerx+1.5,playery-.75;
changeimgcolors 80,0,0,0,0;
changeimgvis 80,1;
changeimgvis 69,1;
}
timeout =.05;
}
if (timeout && keydown(4)&&this.fon==1) {
hideimg 69;
hideimg 80;
this.fon=0;
}
The problem was that the keydown wasn't getting through, and this.fon wasn't getting set to 0

Just in case you don't understand playerchats...
Playerchats is activated as soon as the players hits enter in the text box, and only for a split second.
Hope that helped :-P