[VERY IMPORTANT] How to undo updates....

[mark@neidorff.com]

Hi,

This morning synaptic reported some 32 packages to update.  So I updated
the packages.  After the update I can no longer login (KDE) as myself.  I
can login as myself in a terminal login.  I can also login as root under
KDE (I understand the dangers).

Now I would like to undo the changes that were made by synaptic so that I
can get back to a fully usable system.  How do I find the changed packages
and undo the changes?

Thanks,

Mark