After upgrading from 2012 to 2014 I have this saving problem with certain drawings. I get the "unable to save drawing ..." error, resulting in saving to a tmp file, then I qsave again and it works. It only seems to work for some drawings, and curiously, they are the same types of drawings, although in different folders. They are drawings that have two or three xrefs overlaid, but several copies of each xref in various rotations, if that matters. Also interesting is that I have other drawings that are much larger in size, and with xref's attached, but they don't exhibit any saving problem.
I have tried auditing and recovering these drawings, but to no avail. I suspect it's a timing problem during the save process, but if so, I can't determine if it's a Windows 7 problem, an Autocad 2014 problem, or a hard-drive problem. Any ideas?