In synaptics, you can at least control, what have been the recent updates: File-menu, history.
(if synaptic is startable, with the broken system). So with an apt-...-command, to revert their update, it shouldn't be too hard.
I guess there is a history-command for the command line too.
Maybe you have to delete the whole package, and install a specific version. Afaik, it is possible to install a specific version, but I never had the need to do so.
update: Looked up how to do with apt:
Find packages installed in the last 3x24h:
find /var/lib/dpkg/info/ -name \*.list -mtime -3 | sed 's#.list$##;s#.*/##'
With apt-cache policy, you see available versions of a program:
sudo apt-cache policy PROGRAM:
*** 3.6.7+build3+nobinonly-0ubuntu0.10.04.1 0
500 http://de.archive.ubuntu.com/ubuntu/ lucid-updates/main Packages
500 http://security.ubuntu.com/ubuntu/ lucid-security/main Packages
here 3.6.7 and 3.6.3 . Now you know what earlier version might be installed (often not the immediate predecessor):
sudo apt-get install PROGRAM=3.6.3
Then you need to do an apt-pinning, to prevent future updates:
Create a new file in /etc/apt/preferences.d/ (if >= 10.4) named after your program,
Pin: version 3.6.3*