After resuming my pc from suspend this morning, when I select the Contacts tabs I get a popup telling me that "contactList is undefined". The details button gives this extra info:

message: contactList is undefined
fileName: http://localhost:7633/zimbra/js/zimb...v=080412003741
lineNumber: 415
stack: ([object Object])@http://localhost:7633/zimbra/js/zimbraMail/abook/ZmContactsApp.js?v=080412003741:415 (null)@http://localhost:7633/deskt...

After going back to the setup page the contacts tab is working again.

I also filled bug 27061 against this one.