mailman installation failing

[Noah]

Hi there,

Looks like apt-get is attempting to downgrade mailman, any clues why 
this is happening?  And also why it is failing.  Also the Machine is a 
32 bit machine so I am trying to figure out why 
mailman_1%3a2.1.9-9ubuntu1.2_amd64.deb was ever installed in the first 
place.

# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
   mailman
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
12 not fully installed or removed.
Need to get 0B/8613kB of archives.
After this operation, 0B of additional disk space will be used.
Do you want to continue [Y/n]? y
Preconfiguring packages ...
(Reading database ... 46764 files and directories currently installed.)
Preparing to replace mailman 1:2.1.9-9ubuntu1.1 (using 
.../mailman_1%3a2.1.9-9ubuntu1.2_amd64.deb) ...
  * Stopping Mailman master qrunner mailmanctl 
 
        [ OK ]
dpkg: error processing 
/var/cache/apt/archives/mailman_1%3a2.1.9-9ubuntu1.2_amd64.deb (--unpack):
  subprocess pre-installation script returned error exit status 1
Downgrade detected, from version 0x2010bf0 to version 0x20109f0
This is probably not safe.
Exiting.


noah at enabled:~$ uname -a
Linux enabled.com 2.6.24-24-xen #1 SMP Tue Jun 30 21:53:02 UTC 2009 
x86_64 GNU/Linux
Cheers,

Noah