Apt-get problem

[Ben <ben@ausipos.com>]

I know it's not laptop specific but..
Just wondering if anyone has had problems with apt-get 'Dynamic MMap' ?
If I try to do an update with the following source list:
deb http://security.debian.org/ stable/updates main
deb ftp://mirror.internode.on.net/pub/debian/ stable main contrib non-free
deb ftp://mirror.internode.on.net/pub/debian/ testing main contrib non-free
deb ftp://mirror.internode.on.net/pub/debian/ unstable main contrib non-free

I get this error:
Fetched 2826kB in 1m5s (43.2kB/s)
Reading Package Lists... Error!
E: Dynamic MMap ran out of room
E: Error occured while processing gtkam (NewVersion1)
E: Problem with MergeList 
/var/lib/apt/lists/mirror.internode.on.net_pub_debian_dists_unstable_main_binary-i386_Packages
E: The package lists or status file could not be parsed or opened.

In order for apt-get update to work I have to comment out either:
deb ftp://mirror.internode.on.net/pub/debian/ stable main contrib non-free
deb ftp://mirror.internode.on.net/pub/debian/ testing main contrib non-free

or
deb ftp://mirror.internode.on.net/pub/debian/ unstable main contrib non-fre

as I am running a hodge podge of testing/unstable I really would like to 
be able to use my preferences to define what I am going to download from 
unstable
(mainly KDE & X11) whilst getting the rest from testing. Unfortunately 
this error stops me from doing this.

Any clues what is goin wrong?

( and any ideas how I would set up preferences to download only kde/X11 
from unstable and everything else from testing? I have been reading the 
apt-get howto http://www.debian.org/doc/manuals/apt-howto/index.en.html, 
but can't seem to get my head around it!)

cheers,

Ben.