weird script behaviour

[urgrue <urgrue@tumsan.fi>]

i have script that runs ok from the prompt but doesnt run ok at all 
from cron (yes we've all seen this before, but this time its weirder 
than usually).
i even tried running it with env -i , but i cant reproduce the problem 
at the shell - it only appears when started from cron.
the problem also does NOT appear when started with "at".
i snipped the script down to a bare test minimum and am still able to 
reproduce the error, here it is:

#!/bin/bash

while true
do
sleep 1
echo "start" | logger
ping -n -c 1 -w 3 10.155.11.37 && continue
echo "we didnt continue..... | logger
done

point is to spot if a ping doesnt go.
run from the prompt, it works fine - it pings every second and i never 
get to the "we didnt continue" part.
run from cron, it may or may not run ok for a little while (a minute or 
so), but then it starts to repeatedly reach the "we didnt continue" 
part - and itll keep hitting that part over and over again until i 
intervene.
with a little extra checking, i found out that the ping isn't returning 
zero (as it does from the shell), but its returning 141! where does 
this come from? why does it only start appearing after a minute or so?