Cannot read property 'indexOf' of undefined

Hi
Am getting the following error on Kibana 4 ( 4.0.1 ) . I get this randomly . Cant figure out how to solve this .

TypeError: Cannot read property 'indexOf' of undefined
at Notifier.error (http://kiban4.mini.com:8080/index.js?_b=5930:45607:23)
at Notifier.bound (http://kiban4.mini.com:8080/index.js?_b=5930:32081:21)
at http://kiban4.mini.com:8080/index.js?_b=5930:118772:18
at wrappedCallback (http://kiban4.mini.com:8080/index.js?_b=5930:20873:81)
at http://kiban4.mini.com:8080/index.js?_b=5930:20959:26
at Scope.$eval (http://kiban4.mini.com:8080/index.js?_b=5930:22002:28)
at Scope.$digest (http://kiban4.mini.com:8080/index.js?_b=5930:21814:31)
at Scope.$apply (http://kiban4.mini.com:8080/index.js?_b=5930:22106:24)
at done (http://kiban4.mini.com:8080/index.js?_b=5930:17641:45)
at completeRequest (http://kiban4.mini.com:8080/index.js?_b=5930:17855:7)

Thanks

Agnello