granted this is a little off-topic as knoppix is not involved, but I could get no help on debian.user, so i thought i'd try here:
I have a debian install that started as mepis about 3 years ago.
Wait - don't go just yet. After the sarge release, I switched
my sources.lst to use official debian mirrors. But I had left
both stable and testing entries. I mostly tried to install from
stable. How can I know which packages are more recent than what
sarge offers, and how to judge if a downgrade is possible at all?
Libc6 in particular came from testing - silly me !-)