When configuring a build to execute after another, the setting disappears the
the configuration pages is re-loaded. After the build being triggered is
configured and saved, the correct links are displayed in the GUI, and the build
is correctly triggered. When the configuration of the build being triggered is
loaded, the setting in "Build after other projects are built" is gone, when the
configuration is saved without noticing the missing setting, the link is broken,
and the second build is not triggered. Configuring the triggering build
displays the triggered build in the Post-build Actions section, and does not
break anything.

I imagine the following is irrelevant, but:
OS: Windows XP
Container: Tomcat 5.5.27
Java: 1.6.0_11
Triggering Build: Maven 2 multi-module project
Triggered Build: free-style