Have you checked whether you have password problems? There is an item here eon the Zenoss wiki - http://wiki.zenoss.org/Install_Zenoss .
There is also a discussion her - http://community.zenoss.org/message/74074#74074 .
Note that I HAD installed 4.2.3 with the community install script. I had a good password in all the files referenced in the wiki install note. What had changed was that the 4.2.4 install had changed $ZENHOME/etc/hubpasswd to be admin:zenoss. My fix was to change this file to be admin:<my good password> and restart everything.
The symptoms I was seeing was no polling data appearing anywhere and collectore logfile had messages like:
No service named 'EventService': ZenHub may be disconnected
I have just been through this process and it did work for me (eventually).
Cheers,
Jane