postfix problems after update..

[laurent@blackvoid.org (Laurent Geyer)]

I hope there hasn't been a similar post to this list already but I couldn't find anything in the archives so I figured I'd see if somebody could help me out. I ran an apt-get update and upgrade last night and have since have had problems getting past the postfix preinstallation routine. The upgrade fails with following error message(s):

Preconfiguring packages ...
(Reading database ... 22394 files and directories currently installed.)
Preparing to replace postfix 0.0.19991231pl05-2 (using .../postfix_0.0.20010502.SNAPSHOT-2_i386.deb) ...
Stopping mail transport agent: Postfix.
dpkg: error processing /var/cache/apt/archives/postfix_0.0.20010502.SNAPSHOT-2_i386.deb (--unpack):
 subprocess pre-installation script returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/postfix_0.0.20010502.SNAPSHOT-2_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

I've checked the preinstallation script but couldn't find anything out of the ordinary. Is anybody here aware of the problem and could give me some pointers as to how I would go about fixing it? 

Regards,

Laurent