From: John Hasler on
Artist writes:
> I did not intend that there be upgrades to anything other than stable
> versions. So the aptitude's attempt to upgrade to the 5.1 backport, or
> sid, or whatever, is not what I want. How to I prevent upgrades to
> anything other than stable versions...?

By removing archives other than Stable from your sources.list or by
pinning the packages you don't want upgraded. Google "apt pinning".

> ...and repair the 5.0 installation?

Remove the package and reinstall it. Your configuration will be
preserved.

BTW It's better to use the release name (i.e. "lenny") rather than
"stable" in your sources.list. "Lenny" will always point to the same
archive. When the next release occurs "stable" will abruptly start
pointing to it and if you have "stable" in your sources.list you could
get a surprise upgrade.

These sorts of questions are best directed to the debian-user mailing
list.
--
John Hasler
jhasler(a)newsguy.com
Dancing Horse Hill
Elmwood, WI USA