we have installed Zimbra on our ubuntu server, version: 6.0.7_GA_2473.UBUNTU8 UBUNTU8 FOSS edition
and every while our ZCS web client controls get messed up, although only on Firefox. And then we have to stop and start Zimbra using "zmcontrol stop/start" and everything is fine again, but only for a few days.
Here is a screen shot of what I mean by messed up:

Best regards,