Internet phone service Skype says a "small percentage" of its users have been unable to sign in to its service but it is taking steps to resolve the problem.
Skype said on its website that a corruption issue on computers using Windows, Linux or Macintosh operating systems are behind the access denials.
The company, which is being purchased by Microsoft for $8.5 billion, said it has released a new version of Skype for Windows and plans to release an update for Skype for Mac on Friday. Linux users were told to follow instructions for a manual update.
Skype said individuals using its service on their cell phone, television or other device should be able to continue to sign in as normal.
About 170 million people worldwide use Skype regularly for calls and chats. The service, which allows users to make voice or video calls for free or for a very small amount of money, has become a popular way to avoid large phone bills.
Microsoft's proposed buyout gives the world's biggest software maker the means to sell more digital advertising and offer more popular conferencing tools to help businesses save money.
Skype's services also span hot markets—online socializing, mobile phones and digital video—where Microsoft has been struggling to catch up with Facebook, Apple and Google .