[exim] Strange problem: "unable to set gid"

Hi, list!

I have a very strange problem...
Yesterday, due to an error, an E-Mail was sent to an adress with a forward.
My Exim implements SRS to rewrite the sender in case of forward.
Unfortunately, the recipient (@hotmail.de!! no comment!) had a problem and
hotmail generates a bounce.

Now I see every 10-15 minutes, these errors in the log:

2007-06-18 09:26:11 unable to set gid=12 or uid=100 (euid=65002): localWrite_gw
router (recipient is lucabert@???)
2007-06-18 09:26:11 internal problem in localWrite_gw router (recipient is
lucabert@???): failure to transfer data from subprocess: status=0100
readerror='Resource temporarily unavailable'
2007-06-18 09:26:11 H=(bay0-omc3-s20.bay0.hotmail.com) [65.54.246.220] F=<>
temporarily rejected RCPT <SRS1=XXXXXX>: internal problem in localWrite_gw
router (recipient is lucabert@???): failure to transfer data from
subprocess: status=0100 readerror='Resource temporarily unavailable'
2007-06-18 09:26:11 unexpected disconnection while reading SMTP command from
(bay0-omc3-s20.bay0.hotmail.com) [65.54.246.220]

UID=100 is the uid of my user on the system, and GID=12 is the group mail.
Of course, Exim (with THIS router!) has to problem to deliver E-Mail to the
mailboxes.
Then, why get I this error?

Here my router:

localWrite_gw:
driver = redirect
allow_filter
domains = +local_domains
user = ${lookup mysql {select case count(*) when 0 then 65002 else case uid
when 0 then 65002 else uid end end from aliases left outer join account on
aliases.accountid=account.id left join domain on aliases.domainid=domain.id
where lower(aliasname) = lower('${quote_mysql:$local_part}') and
lower(domainname) = lower('$domain')}}
group = 12
data = ${lookup mysql {select concat('# EXIM Filter\n\n',
replace(concat(concat(case hasAutoresponder when 'f' then '' else
replace(replace('if not error_message and \$message_headers does not contain
"\\\\nX-SPAM:" and \$message_headers does not contain "\\\\nX-Infected:" then
if personal then mail text "%%TEXT%%" from "$local_part@$domain" subject
"%%SUBJ%%" extra_headers "MIME-Version: 1.0\\\\nContent-Type: text/plain;
charset=ISO-8859-15" endif endif', '%%SUBJ%%', autoresponderSubject),
'%%TEXT%%', autoresponderText) end, '\n\n'), dataHam), '%%FINALDEST%%',
finaldest)) from aliases left join account on aliases.accountid=account.id left
join domain on aliases.domainid=domain.id where lower(aliasname) =
lower('${quote_mysql:$local_part}') and lower(domainname) = lower('$domain')}}
redirect_router = loopbackRouter
reply_transport = autoresponder
pipe_transport = address_pipe
file_transport = address_file
directory_transport = address_file
headers_remove = ${if def:h_X-DefSubject {Subject}}:X-DefSubject:
headers_add = ${if def:h_X-DefSubject {Subject: $h_X-DefSubject:}}
srs = forward
srs_condition = ${if match {${lookup mysql {SELECT dataHam FROM aliases left
join account on aliases.accountid=account.id left join domain on
aliases.domainid=domain.id where lower(aliasname) =
lower('${quote_mysql:$local_part}') and lower(domainname) = lower('$domain')}}}
{.*deliver.*} {yes}{no}}
no_more

Has someone an idea?

Thanks
Luca Bertoncello
(lucabert@???)