ISSUE:
"This file cannot be saved because some properties are missing or invalid" message when a user is trying to save a Word document with a Quick part, back to a SharePoint site, when the quick part has line breaks in the multi-line column content type.
CAUSE:
The problem is seen after installing an update to Office 2010 and the version of Office is 14.0.7102.5004 or higher.
SOLUTION:
Install hotfix per article 2878228 - http://support.microsoft.com/kb/2878228
The resolution is also included in the February 2014 Cumulative update for MSO.dll.