Last week SharePoint users have reported issue with multi-line field used in custom content type used in SharePoint 2010 document libraries.
Users were not be able to save documents on the server (in a document library) as 'word' would prompt them with a "Required properties" error message stating: ".. correct the invalid or missing required properties"
After some research I found out that removing the following update KB2760758 would fix the problem.
Obviously this is not an acceptable solution and I would like to know if this issue has been reported and a fix would be issued sooner than later.