Wow, this is a LONG thread.
Here's a recap of my experience with the issue; hopefully MSFT is still monitoring the thread and working on the problem.
I've been able to recreate the error on Win 7, 8 and 8.1, always with PowerPoint 2013. I have a Lenovo Thinkpad Carbon X1 with 8GB RAM, Core i7 processor and SSD.
The Red-X issue usually occurs for me when saving very large (8MB - 11MB) PPTX files (with lots of graphics), although I think I've seen it on smaller ones as well. I can recreate it by repeatedly (and quickly) making a change and then saving. For example,
repeatedly pasting a graphic with Cntl-V and Saving with Cntl-S. Of course, I often receive the error when not trying to do so.
I use OneDrive, Box, and Carbonite.
Here are some results of my limited testing/troubleshooting:
Saving to Box-monitored folder with Carbonite running - receive error
Saving to Box-monitored folder with Carbonite paused - receive error
Saving to non-Box, non-OneDrive folder with Carbonite running - receive error
Saving to non-Box, non-OneDrive folder with Carbonite paused - receive error
With Carbonite *uninstalled,* I cannot reproduce the error saving to Box or OneDrive.
I have installed and uninstalled Carbonite several times to confirm these results (admitedly not comprehensive, but I don't have more time to be a beta tester :) ) I must admit, I'm baffled as to why I have to uninstall Carbonite, vs. just pausing it. It
seems like others in the thread have been successful with just pausing their backup software... Oh well, my coding/debugging days are too far in the past for me to dig deeper into that one!
I started having this issue in Feb 2013 when I bought my laptop with Win 8 and Office 3013 (including SkyDrive, at the time), and Carbonite. At the time I had suspected either a SkyDrive issue or Win 8 issue, which led me to move to back to Win 7 and then
to replace SkyDrive with Box.com. Still experiencing the issue, I moved back from PowerPoint 2013 to 2010, and I did not see the issue for a year (with Carbonite running) until I re-imaged my laptop last week with Win 8.1, Office 2013, Box and Carbonite.
So, for me, I'm heading back to PowerPoint 2010 (again). Saving files as 2007/PPT is too irritating with the compatibility pop-up warnings. And running without Carbonite (or another backup) is out of the question. Thanks for all the great posts here -
the comments have saved me time experimenting with CrashPlan (which I like, BTW) or another backup solution.
Maybe I'll try 2013 again in 6 months. Until then, I'll be watching this thread!