Ugly fonts when upgrading

[Doug Neville-Dove <d.neville-dove@trowcom.co.uk>]

I'm running Woody on a Toshiba Satellite 1800-700.
When-ever I try to upgrade anything that includes X11, Konqueror,
Evolution or Mozilla or any fonts in general - my fonts get messed up
completely and are unusable. 
I'm using KDE 3.1.1 and the KDE bit seems relatively unharmed, but app's
such as Kismet get wrecked - and in particular Evolution is ruined.

Can anyone give me a pointer how to reconfigure these fonts after an
upgrade - or even better how to avoid getting trashed when I upgrade.

Luckily I keep a ghost so I can roll back - but this is driving me
bonkers.

Thanks

Doug