This weekend, Facebook disabled the app and "single sign on" service for the online music streaming service Grooveshark. While Grooveshark initially apologized in a blog post, saying the disabled services must have been an error on Facebook's part, Digital Music News confirmed that Facebook actually cut ties with Grooveshark due to a copyright infringement complaint the social media giant received.

"We have removed the Grooveshark app due to a copyright infringement complaint we received," Facebook officially stated. Facebook has not yet responded to our request for further comment.

At the moment, users can not sign into Grooveshark with a Facebook username and password, or post tracks on Facebook via the Grooveshark Facebook app. Grooveshark has not made any public statements since the blog post this weekend, which incorrectly claimed, "We believe [the services] were disabled in error and we are in communication with Facebook to try to understand exactly what’s going on, so we hope to see a resolution to these problems soon." The post also said Grooveshark issued a temporary fix to the single sign-on issue, allowing those users with Facebook log-ins to sign on with their e-mail addresses.

The online music streaming service has been the target of many copyright infringement complaints where similar services like Rdio and Spotify haven't, in part because Grooveshark allows users to upload their own music and share it with others. While Grooveshark says it takes down tracks in response to DCMA infringement notices, that hasn't stopped the service from getting into hot water with four major record labels (EMI, Universal, Sony, and Warner) earlier this year.

Facebook's recent move promises to cause huge headaches for the already embattled Grooveshark. And some companies may be concerned by the fact that Facebook can, without warning, revoke access to the log-in service that they depend on to authenticate large portions of users every day.

When Ars asked a spokesperson for Grooveshark whether the company was doing anything to rectify its Facebook issues, she responded that Grooveshark was not sharing any details beyond Facebook's public statement citing a copyright infringement complaint.