I just had the same error. Constant alert sounds whenever I clicked in the editor and had no idea what was causing it until I came to this thread. Then I looked in the editor log and indeed found the error:
Preference shared sync write failed
disabling and reenabling sync file solved it.
I really think that a warning of sort should appear in the editor to indicate the error...as it is now, it's quite difficult to guess where the problem is coming from.
And if the sync file or the path to sync file is corrupted/lost the consequences could be quite annoying for anyone using the function. So the sooner the user is warned the better. Thanks.