Can you post a screenshot? (shift+command+4, then drag a box around what you want to capture--.pngs will be saved to the desktop)
I am not an expert, but I believe the error you are getting is because there is a flag set in the preferences file that is not part of the standard set in the manifest. I'm not sure what that would be because I don't have your preferences file or the standard manifest, but if you move your .plist file to the desktop and then relaunch Safari it will recreate one that should match the manifest. Did you use terminal to manually change some Safari settings?
Note that having preferences that don't match the manifest don't actually stop them from being sent out apparently. See »support.apple.com/kb/HT3933
for an example.--
I use Linux, OS X, iOS and Windows. Let the OS wars die.