Skype is experiencing software problems that have disconnected service for millions of users.

The company, which was acquired by eBay, notified users on its Web site that some customers may be having problems logging into the Internet calling service.

“Some of you may be having problems logging into Skype,” the notice states. “Our engineering team has determined that it’s a software issue. We expect this to be resolved within 12 to 24 hours. Meanwhile, you can simply leave your Skype client running and as soon as the issue is resolved, you will be logged in. We apologize for the inconvenience.”

Downloads of Skype software have been temporarily disabled as well, the notice states, which added that Skype will make downloads available again “as quickly as possible.”

At the time of eBay’s $2.6 billion purchase of the company in October 2005, Skype had 54 million members in 225 countries and territories, and was signing up 150,000 new users each day.

The New York Times reported that Skype users in Colombia, Brazil, Germany, Finland and the United States reported difficulties logging on, and there were 29 posts on the Skype blog lamenting the lack of connections.

Network World could not access the blog, which had 61 reactions on it, at the time of this report – attempts produced a “Sorry, this isn’t working right now. Please try again” notification.

Skype uses peer-to-peer technology to connect phone calls, instant messages and videos among its users, and supports the Windows, Mac OS X, PocketPC and Linux operating systems. The service is popular with consumers and some small- to medium-size businesses, but Skype is also trying to crack the large corporate market.

Skype net revenues totaled a record $90 million in Q2 2007, a growth rate of 103% over the $44 million reported in Q2 2006.

Skype had 220 million registered user accounts at the end of Q2 2007, representing a 94% increase from the 113 million registered user accounts at the end of Q2 2006.