[Hampshire] Broken packages in Lenny - possible solutions?

I am running KDE 3.5.10 on a fully updated Lenny. KMail is 1.9.9.

For about 3 weeks now KMail has been broken. I have had broken major
packages before on Lenny, namely CUPS and OOo. OOo broke whilst it was being
updated to 2.4.1. I don't know whether CUPS was also being updated. Both
were fixed quite rapidly. (After a few days.)

This time KDE was being updated from 3.5.9 to 3.5.10.

I have had it suggested on the Debian list that that is my lot for KMail on
Lenny, so tough.

I have tried to get rid of KDE and start again, in case the breakage is on my
computer, tho' someone on the KDE_PIM list was having the same problems with
KMail and IMAP. I use POP3.

My last effort was:

aptitude purge kde kmail

followed by a hard reboot

followed by

aptitude install KDE

It was a total failure. Nothing was downloaded and everything remained
exactly as it had been, even down to the exact files I had been using
immediately before the purge still being in place and the same websites open.
So much for purge removing configuration files. :-(

Is there a way of doing what I was trying to do? I.e. get rid of KDE and
install it again with a clean slate. Or even better, do the same thing just
with KMail itself? Or do I have to format the HDD and reinstall the entire
OS to achieve that?

This seems to me to be a Debian problem rather than a KDE one. And also
probably BKAC. :-( The broken package that I am trying to sort out happens
to be KDE, but it is the package manager that is failing to purge, and doing
so in a way that I do not understand and cannot succeed in rectifying.

TIA
Lisi