Millions of Skype users were having trouble on Tuesday signing into the application, less than two weeks after the company published software updates for Windows and Mac computers to fix a similar problem.
Skype said it had identified the latest issue as a configuration problem.
"We've identified the cause of the problem, and have begun to address it," wrote Peter Parkes of Skype just after 1 p.m. GMT. "If you've been affected, you should start to see improvement in the next hour or so. You shouldn't need to manually sign back in to Skype - it should reconnect automatically when it's able to do so. We apologize for the disruption to your conversations."
Skype's website said that more than 22 million users were online around 12 p.m. GMT. But a half hour later, the figure fell to around 16 million, then around 2.2 million by 1 p.m. GMT. Overall, Skype has about 170 million users.
Skype officials were unavailable for an immediate comment.
Twitter was rife with comments from users complaining about the outage. Jokingly, many users referred to the company's recent acquisition by Microsoft for US$8.5 billion as a possible source for the problems. The deal is still subject to regulatory review, so as of yet, Microsoft is not involved yet in Skype's operations. The companies said it expects to have regulatory clearances finished by the end of the year.
"Microsoft bought Skype," wrote one Twitter user. "The entire Skype network is not working at the moment. Coincidence?"
On May 26, Skype released an update for Windows that fixed what it called "a corruption" that occurred in some users' systems. The issue was a shared.xml configuration file that prevented users from signing in to the application.
Skype followed up shortly after the Windows release by issuing an update for Apple's Mac OS.