Comment 2 for bug 1071293

I commented in the french version of the bug as well, I'll post the same, it could help the ones in my very same situation:

I confirm this. The issue is in the init scripts for the agent, for the server and for the proxy. The issue has been fixed in the 2.0.3 version of the package (I did a comparison of the init scripts between 2.0.2 and 2.0.3).
Apparently there's a wrong evaluation in the _ev_ function on lines 28-30 which throws an exit status of 1 despite the daemon being started properly. Dpkg gets the exit status of 1 and thinks some issue occurred during installation, leaving the package in an inconsistent state.
Here, this is the NON-working version from zabbix 2.0.2:

_ev_ () {
  [ "$VERBOSE" != "no" ] && eval $@
}

This is the working version from the package zabbix 2.0.3 (from Ubuntu Raring):

_ev_ () {
  [ "$VERBOSE" = "no" ] || eval $@
}

The solution is to copy the init scripts from the Raring version of the package (or fix the above function), recompile the deb package and everything should be fine.