Zsh hangs sometimes?

["Kamil Jońca" <kjonca@poczta.onet.pl>]

I have some maildirs and some mails (files with mails are) duplicated.
(But I don't want to pass them through formail -D)
I wrote script to find duplicates:

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export IFS="
" ;find -type d -not -name cur -not -name tmp -not -name new -not -name "." -not -name ".." | while read q ; do echo $q ; find "$q" -maxdepth 2 -type f |while read w ; do  find "$q" -maxdepth 2 -type f |while read e ; do if [[ "$w" < "$e" ]] ; then ; if cmp -s "$w" "$e" ; then echo "$w" "$e" identical ; fi ; fi ; done;done;done

==============================
And sometimes this hangs :( 
there's not child processes.

Moreover if I put loops in the subshells (ie. |( while read q ; ....|(while read w ... ) ...) )
then everthings luks good.
Am I missing something?
zsh 4.3.6 (i686-pc-linux-gnu)
Debian GNU/Linux lenny/sid
Linux alfa.kjonca 2.6.25+1 #2 PREEMPT Tue Apr 29 12:44:38 CEST 2008 i686 GNU/Linux

KJ


PS. I know about O(n^2) comparisions between files.