Update: Google has fixed problems to its Talk instant messaging service after users around the world were unable to use the tool.
The incident first came to light just before midday UK time, and lasted throughout the afternoon, but by 4:25pm the firm claimed it had fixed the issue on its App Status Dashboard.
"The problem with Google Talk should be resolved. We apologise for the inconvenience and thank you for your patience and continued support," it said.
The firm stressed that "system reliability is a top priority at Google" but the incident underlines the potential problems that can be caused by using free cloud-hosted services without guaranteed service levels.
Google has confirmed that an unspecified issue with its Talk service has resulted in the majority of users being unable to access its instant messaging system.
The issue with Google Talk first emerged just before midday UK time, with Google's first acknowledgement published at 11:40, as the tool fails to work as a standalone client or within Gmail.
Initially, Google had expected to resolve the matter quickly, promising it would let users know the time frame for fixing the issue.
“We're aware of a problem with Google Talk affecting a majority of users. The affected users are able to access Google Talk, but are seeing error messages and/or other unexpected behaviour," Google said on its status alert web page.
"We will provide an update 12:50PM detailing when we expect to resolve the problem. Please note that this resolution time is an estimate and may change."
But the service is still down at the time of writing and Google has been unable to provide any indication of when Google Talk will be back online, with the next update scheduled at 14:50.
None of the other services listed on Google's Apps Status Dashboard appear to be suffering problems.
Google has a decent track record of dealing with service interruptions. Earlier this year, an outage of its Gmail service was addressed in little over an hour.