I get the following error in the firefox javascript console when I mouseover a zimlet that I constructed using the BUGZ zimlet as a template. Any ideas?

Error: [Exception... "'AjxException' when calling method: [nsIOnReadyStateChangeHandler::handleEvent]" nsresult: "0x8057001c (NS_ERROR_XPC_JS_THREW_JS_OBJECT)" location: "<unknown>" data: no]