Google Talk, the US tech giant\'s messaging and telephony service, was knocked offline Thursday for unknown reasons, the company said. A Google status page said the service appeared to be malfunctioning around 1040 GMT, with the outage continuing more than three hours later. \"We\'re aware of a problem with Google Talk affecting a majority of users,\" the status page said. \"The affected users are able to access Google Talk, but are seeing error messages and/or other unexpected behavior.\" At 1340 GMT, the page said, \"we are continuing to investigate this issue.\"