Thank you for your help, Xavier.

I'm root, and here are the results of 'apt-get update':

Hit <ftp://ftp.fr.debian.org> stable/main Packages
Hit <ftp://ftp.fr.debian.org> stable/main Release
Hit <ftp://ftp.fr.debian.org> stable/non-free Packages
Hit <ftp://ftp.fr.debian.org> stable/non-free Release
Hit <ftp://ftp.fr.debian.org> stable/contrib Packages
Hit <ftp://ftp.fr.debian.org> stable/contrib Release
Hit <ftp://ftp.fr.debian.org> stable/main Sources
Hit <ftp://ftp.fr.debian.org> stable/main Release
Hit <ftp://ftp.fr.debian.org> stable/non-free Sources
Hit <ftp://ftp.fr.debian.org> stable/non-free Release
Hit <ftp://ftp.fr.debian.org> stable/contrib Sources
Hit <ftp://ftp.fr.debian.org> stable/contrib Release
Get:1 <http://http.us.debian.org> sarge/main Packages [3231kB]
Hit <http://security.debian.org> stable/updates/main Packages
Hit <http://security.debian.org> stable/updates/main Release
Hit <http://security.debian.org> stable/updates/contrib Packages
Hit <http://security.debian.org> stable/updates/contrib Release
Hit <http://security.debian.org> stable/updates/non-free Packages
Hit <http://security.debian.org> stable/updates/non-free Release
Get:2 <http://non-us.debian.org> stable/non-US/main Packages
[44.5kB]
Hit <http://non-us.debian.org> stable/non-US/main Release
Hit <http://non-us.debian.org> stable/non-US/contrib Packages
Hit <http://non-us.debian.org> stable/non-US/contrib Release
Hit <http://non-us.debian.org> stable/non-US/non-free Packages
Hit <http://non-us.debian.org> stable/non-US/non-free Release
Get:3 <http://non-us.debian.org> stable/non-US/main Sources
[18.7kB]
Hit <http://non-us.debian.org> stable/non-US/main Release
Get:4 <http://non-us.debian.org> stable/non-US/contrib Sources
[579B]
Hit <http://non-us.debian.org> stable/non-US/contrib Release
Get:5 <http://non-us.debian.org> stable/non-US/non-free
Sources [971B]
Hit <http://non-us.debian.org> stable/non-US/non-free Release
Get:6 <http://non-us.debian.org> stable/non-US/main Packages
[44.5kB]
Hit <http://non-us.debian.org> stable/non-US/main Release
Hit <http://non-us.debian.org> stable/non-US/contrib Packages
Hit <http://non-us.debian.org> stable/non-US/contrib Release
Hit <http://non-us.debian.org> stable/non-US/non-free Packages
Hit <http://non-us.debian.org> stable/non-US/non-free Release
Get:7 <http://non-us.debian.org> stable/non-US/main Sources
[18.7kB]
Hit <http://non-us.debian.org> stable/non-US/main Release
4% [2 Packages gzip 0] [Logging in] [1 Packages 19916/3231kB 0%]
gzip: stdin: not in gzip format
Err <http://non-us.debian.org> stable/non-US/main Packages
  Sub-process gzip returned an error code (1)
4% [3 Sources gzip 0] [Waiting for file] [Query] [1 Packages
19916/3231kB 0%]
gzip: stdin: not in gzip format
Err <http://non-us.debian.org> stable/non-US/main Sources
  Sub-process gzip returned an error code (1)
Get:8 <http://non-us.debian.org> stable/non-US/contrib Sources
[579B]
Hit <http://non-us.debian.org> stable/non-US/contrib Release
Get:9 <http://non-us.debian.org> stable/non-US/non-free
Sources [971B]
Hit <http://non-us.debian.org> stable/non-US/non-free Release
5% [6 Packages gzip 0] [Query] [1 Packages 43084/3231kB 1%]
gzip: stdin: not in gzip format
Err <http://non-us.debian.org> stable/non-US/main Packages
  Sub-process gzip returned an error code (1)
5% [7 Sources gzip 0] [Query] [1 Packages 43084/3231kB 1%]
gzip: stdin: not in gzip format
Err <http://non-us.debian.org> stable/non-US/main Sources
  Sub-process gzip returned an error code (1)
5% [8 Sources gzip 0] [Query] [1 Packages 43084/3231kB 1%]
gzip: stdin: not in gzip format
Err <http://non-us.debian.org> stable/non-US/contrib Sources
  Sub-process gzip returned an error code (1)
Err <http://non-us.debian.org> stable/non-US/non-free Sources
  Could not open file
/var/lib/apt/lists/partial/non-us.debian.org_debian-non-US_dists_stable_non-US_non-free_source_Sources
- open (2 No such file or directory)
5% [Query] [1 Packages 43084/3231kB 1%]
gzip: stdin: Resource temporarily unavailable
Hit <ftp://ftp.debian.org> stable/main Packages
Hit <ftp://ftp.debian.org> stable/main Release
Hit <ftp://ftp.debian.org> stable/non-free Packages
Hit <ftp://ftp.debian.org> stable/non-free Release
Hit <ftp://ftp.debian.org> stable/contrib Packages
Hit <ftp://ftp.debian.org> stable/contrib Release
Hit <ftp://ftp.debian.org> stable/main Sources
Hit <ftp://ftp.debian.org> stable/main Release
Hit <ftp://ftp.debian.org> stable/non-free Sources
Hit <ftp://ftp.debian.org> stable/non-free Release
Hit <ftp://ftp.debian.org> stable/contrib Sources
Hit <ftp://ftp.debian.org> stable/contrib Release
Get:10 <http://http.us.debian.org> sarge/main Release [81B]
Get:11 <http://http.us.debian.org> sarge/contrib Packages [61.7kB]
Get:12 <http://http.us.debian.org> sarge/contrib Release [84B]
Get:13 <http://http.us.debian.org> sarge/non-free Packages
[61.5kB]
Get:14 <http://http.us.debian.org> sarge/non-free Release [85B]
Fetched 3356kB in 9s (357kB/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/source/Sources>
 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)
Failed to fetch
<http://non-us.debian.org/debian-non-US/dists/stable/non-US/main/source/Sources>
 Sub-process gzip returned an error code (1)
Failed to fetch
<http://non-us.debian.org/debian-non-US/dists/stable/non-US/contrib/source/Sources>
 Sub-process gzip returned an error code (1)
Failed to fetch
<http://non-us.debian.org/debian-non-US/dists/stable/non-US/non-free/source/Sources>
 Could not open file
/var/lib/apt/lists/partial/non-us.debian.org_debian-non-US_dists_stable_non-US_non-free_source_Sources
- open (2 No such file or directory)
Reading Package Lists... Error!
W: Couldn't stat source package list
<http://non-us.debian.org> stable/non-US/main Packages
(/var/lib/apt/lists/non-us.debian.org_debian-non-US_dists_stable_non-US_main_binary-i386_Packages)
- stat (2 No such file or directory)
W: Couldn't stat source package list
<http://non-us.debian.org> stable/non-US/main Packages
(/var/lib/apt/lists/non-us.debian.org_debian-non-US_dists_stable_non-US_main_binary-i386_Packages)
- stat (2 No such file or directory)
W: Couldn't stat source package list
<http://non-us.debian.org> stable/non-US/main Packages
(/var/lib/apt/lists/non-us.debian.org_debian-non-US_dists_stable_non-US_main_binary-i386_Packages)
- stat (2 No such file or directory)
W: Couldn't stat source package list
<http://non-us.debian.org> stable/non-US/main Packages
(/var/lib/apt/lists/non-us.debian.org_debian-non-US_dists_stable_non-US_main_binary-i386_Packages)
- stat (2 No such file or directory)
W: Duplicate sources.list entry <http://non-us.debian.org>
stable/non-US/contrib Packages
(/var/lib/apt/lists/non-us.debian.org_debian-non-US_dists_stable_non-US_contrib_binary-i386_Packages)
W: Duplicate sources.list entry <http://non-us.debian.org>
stable/non-US/non-free Packages
(/var/lib/apt/lists/non-us.debian.org_debian-non-US_dists_stable_non-US_non-free_binary-i386_Packages)
E: Dynamic MMap ran out of room
E: Error occured while processing odontolinux (NewVersion1)
E: Problem with MergeList
/var/lib/apt/lists/http.us.debian.org_debian_dists_sarge_main_binary-i386_Packages
E: The package lists or status file could not be parsed or
opened.


Sorry for this large message...