Google has issued a status alert for Google Drive.
"Some users of the Google Drive Sync client for Windows will receive the error message "Sorry, Backup and Sync needs to quit" and will be unable to use the client.
Other Sync clients are not affected.
Affected users may continue using the Google Drive web interface and mobile applications.
We have identified the root cause of the issue and are implementing a potential fix now."
Further information can be found at the Google Apps status dashboard - https://www.google.com/appsstatus
We'll update this ticket when we know more.