Code:
2008-10-17 03:01:39,986 ERROR [btpool0-11] [name=XXXXX@XXXXXXXX.com;mid=382;ip=XXX.XXX.XXX.XXX;ua=ZimbraWebClient - FF2.0 (Win)/5.0.9_GA_2533.RHEL5;] ObjectHandler - loadHandler caught exception
com.zimbra.cs.object.ObjectHandlerException: null handler for com_zimbra_tracking
at com.zimbra.cs.object.ObjectHandler.<init>(ObjectHa ndler.java:55)
at com.zimbra.cs.object.ObjectHandler.loadHandler(Obj ectHandler.java:95)
at com.zimbra.cs.object.ObjectHandler.getObjectHandle rs(ObjectHandler.java:77)
at com.zimbra.cs.mime.MimeHandler.getObjects(MimeHand ler.java:246)
well looking at the log file it appears that the zimlet com_zimbra_tracking is causing the issue. You could try un-deploying it and then deploy it again.