[Exim] Urgent: Exim failing on production server

I desperately need some assistance, and am hoping someone reading this
newsgroup can help:

Our production mail server has been working reliably up until yesterday, at
which time the deliveries started failing. The associated error messages are
nearly identical:

<-- BEGIN LOG -->
LOG: 0 MAIN
Unfrozen by forced delivery
LOG: 0 MAIN
** <email info removed> R=lookuphost T=remote_pipe: Child process of
remote_pipe transport returned 134 (could mean shell command ended by signal
6 (Abort)) from command: /usr/bin/env
LOG: 0 MAIN
Frozen (delivery error message)
<-- END LOG -->

The return code 134 is constant -- although at times the command referred to
is an in-house Perl script (which has worked flawlessly for months). Most of
the time, however, the failing command is usually /usr/bin/env!?

I have tried forcing the delivery, rebooting the server itself, and have
scoured the system logs for something to identify the source of the problem.
No luck. I am completely lost.

The OS and mailer version(s) are:

# ./exim -bV
Exim version 3.13 #7 built 01-Jun-2000 10:07:35
Copyright (c) University of Cambridge 1999


# uname -impsvr
SunOS 5.7 Generic_106541-04 sun4u sparc SUNW,UltraSPARC-IIi-cEngine

If anyone has *any* suggestions as to where I might even start looking, I
would be extremely grateful.

My, ahem, employment might be at stake :(


--
Whitney Williams