Oculus Rift users discovered today that their headphones did not work, and the problem seems to be a single expired certificate, as reported by Neowin. The certificate, which is part of the Oculus Runtime service, is read as invalid, and it is likely that the cause is a simple error, such as someone forgetting to extract a new file.
The file that causes problems is called OculusAppFramework.dll and must be updated so that the headphones and software run normally. The error message that users are seeing as a result says, "Your Oculus software may be updating. Please wait a minute and try again. If the problem persists, contact Oculus support."
For now, the problem can be fixed temporarily by setting the date of your computer no later than March 7. The problem is not huge and will probably be solved quickly once Oculus issues a software update, but it's annoying if you're trying to use your headphones today.