Often the logs will show the task being received, and may show an error as well. Not always, but often. It's always worth looking.
You could also verify if the deploy cab file actually copied down to the system. If there were problems getting the file there, and if it didn't decompress and creat the sysprep folder, then you'd have some issues with running sysprep. :D
Don't know off the top. Unfortunately that's not a very common error, and unfortunately a -1 error simply means "fails" so it says pretty much nothing.