[exim] Pipe command trying to change to /root directory?

Trying to run a perl program in a filter as follows:

     pipe "/usr/bin/perl /etc/exim/scripts/hashhack.pl"

But get this result:

2006-05-30 06:47:45 1Fl4ZJ-000587-Co == |/usr/bin/perl
/etc/exim/scripts/hashhack.pl <shryer@???> R=spamtap_filter
T=special_pipe defer (13): Permission denied: failed to chdir to /root

The router looks like this:

spamtap_filter:
driver = redirect
allow_filter
allow_freeze
allow_fail
check_ancestor
no_check_local_user
no_expn
file = /etc/exim/filter-spamtap
file_transport = address_file
pipe_transport = special_pipe
reply_transport = address_reply
retry_use_local_part
skip_syntax_errors
user = mail
modemask = 2
no_verify


What am I doing wrong? Stumped.