(Serious) Problem with apt-get

[Arturo Ramos <aramos@unizar.es>]

Since some time, when doing apt-get update, my Debian box (Debian/GNU 
Linux 3.0) ends with an error like this (although before it worked well)


Hit ftp://ftp2.it.debian.org unstable/contrib Release
Fetched 44.5kB in 2s (19.3kB/s)
Failed to fetch 
http://non-us.debian.org/debian-non-US/dists/stable/non-US/main/binary-i386/Packages 
 Sub-process gzip returned an error code (1)
Failed to fetch 
http://non-us.debian.org/debian-non-US/dists/stable/non-US/main/binary-i386/Packages 
 Sub-process gzip returned an error code (1)
Reading Package Lists... Error!
E: Dynamic MMap ran out of room
E: Error occured while processing octave2.1-headers (NewVersion1)
E: Problem with MergeList 
/var/lib/apt/lists/ftp2.it.debian.org_debian_dists_unstable_main_binary-i386_Packages
E: The package lists or status file could not be parsed or opened.


And stops. Could anybody help me please? Thanks in advance.

Arturo Ramos