I've viewed a few threads on this already, so sorry for the redundancy. I haven't been able to sign in to Messages since updating to Mavericks. I've tried: -Resetting the keychain -Changing the DNS servers -Checking the date & time -And all of these steps: "If that does not work use the Finder > Go Menu whilst holding down the ALT key Select the Library that appears. Navigate to Containers/com.apple.ichat/Data/Library/Preferences In here find the com.apple.imessages.bag.plist This should not be an Alias. If it is a regular file Drag it to the Trash and Restart Messages. This .plist holds the server info that Messages is trying to use for the iMessages account. If that does not work:- Whilst the Finder window is open use the View Menu > Show Path Bar. Double Click the Library item next to your Little House icon. Navigate to Preferences. In here find com.apple.ids.service.com.apple.madrid.plist and drag that to thre Trash and then Restart Messages. This may need you to re-enter your Apple ID. If that does not work find the com.apple.imagent.plist and Drag that to the Trash In this case Restart the computer." Not sure what information is relevant, but it's a Mid 2010 Macbook Pro, running OS X 10.9 I'm not all that computer literate, so it's possible I messed up one of the steps, but I don't have Apple Care anymore, so I assume I can't take it to the Genius bar. Are there any further steps I can take before giving up completely?