Oops. Your chat connection may have been interrupted – Google Chat Help: “Update: I can confirm that this is a known issue. We’re working to resolve it, but it could be a little while until we get it fixed. In the meantime, disabling outbound Google Voice calls as is suggested above should resolve it.
However, keep in mind that sometimes this is a legitimate error that can appear in low bandwidth scenarios. If you’ve disabled outbound Voice but occasionally get this error, it’s not the same issue we’re currently experiencing.”