Apt Sources.list question

I'm curious i've been running Debian Etch 4.0 on my desktop machine for a year now and yesterday I checked the sources.list file and compared it to a fresh install of Debian Etch 4.0R3 on my laptop's sources.list file and it say's stable in the laptops sources.list file which is fine and all but my desktop machine has been having a problem for quite some time i'm curious if if this problem is the reason for what i'm experiencing on my desktop machine! Well anyway on to the problem.. like I was saying I checked both the sources.list file on both computers the laptops is fine and here is the one on my desktop machine:

#
# deb cdrom:[Debian GNU/Linux testing _Etch_ - Official Beta i386 CD Binary-1 2$

deb cdrom:[Debian GNU/Linux testing _Etch_ - Official Beta i386 CD Binary-1 200$

deb http://ftp3.nrc.ca/debian/ lenny main
deb-src http://ftp3.nrc.ca/debian/ lenny main

deb http://security.debian.org/ lenny/updates main contrib
deb-src http://security.debian.org/ lenny/updates main contrib

now what's interesting is I installed etch 4.0 when it came out and have been updating it and all of the packages on the system normally for about a year now. What's interesting is it was the stable version of etch I installed not the testing version of lenny at the time. For quite some time my destkop machine won't update properly or install the packages I'm trying to update. The error I receive says this Fatal Error: Assuming Package is installed or exists, this has gone on for closer to 6 months and haven't been able to figure out why it won't update properly. I spoke to a friend who runs debian as well and he hasn't seen this problem but he had said to me I must have done something by accident to mess with the sources.list file and it changed the label from stable to testing and when I apt-get update and the like he seems to think that it's trying to look for the stable packages in the stable repository of etch and not the testing is it possible this could be conflicting with something and not allowing me to upgrade properly? Thoughts?

Thanks Eric :-)

Comments

Do you have a file: /etc/apt/apt.conf? What is in it?
If lenny is not in that file, then no upgrades will work.

If you want to upgrade to lenny, use: apt-get update && apt-get -u dist-upgrade
This will probably break many things.

To stay in etch, change all the lenny to etch in /etc/apt/sources.list and then: apt-get clean && apt-get update