SharePoint 2010: File locked for editing by xxx

In SharePoint 2010 it is very frequent to see users complaining of encountering this particular error when they try to edit a file in Office 2010 client.

It is because the SharePoint server will attempt to check every 10 minutes whether the user performing the edit still has the file handle open for editing.

According to the KB - waiting 10 minutes usually resolves the problem - http://support.microsoft.com/kb/899709

Sometimes, even though the user has checked in.closed the file after making his changes, other users still could not access the file for editing.