Instead of overwriting saved games, you could save a couple times under unique names, then delete older saves if you know one of the more recent ones works. Would be a bit of a pain though... <img src="/ubbthreads/images/graemlins/disagree.gif" alt="" />
I found a post where someone said this problem went away after they started saving multiple times, but that was pretty much all they said. A couple other topics (though no solutions);
1.34 Patch causing corrupt savesSaved games keep corruptingSysinternals has a freeware utility
Filemon, which may be useful in tracking down this problem.
Filemon monitors and displays file system activity on a system in real-time. Its advanced capabilities make it a powerful tool for exploring the way Windows works, seeing how applications use the files and DLLs, or tracking down problems in system or application file configurations. Filemon's timestamping feature will show you precisely when every open, read, write or delete, happens, and its status column tells you the outcome. Filemon is so easy to use that you'll be an expert within minutes. It begins monitoring when you start it, and its output window can be saved to a file for off-line viewing. It has full search capability, and if you find that you're getting information overload, simply set up one or more filters.
If you are so inclined, start Divinity and load a game, start Filemon, stop monitoring and clear the list, add a filter so it is only monitoring the Divinity folders, start monitoring, save a game in Divinity under a new name, then save Filemon's list. Maybe that could help the Larians figure out what is happening, if they see what is going on during a save which gets corrupted?