When it happens have you tried Save As to create a project with a different filename? 

karhide
When it happens have you tried Save As to create a project with a different filename? 

yes and even tried to save it to a different HD - no effect

Hi. Have you tried save copy as? I had a stubborn old project a few weeks ago that I could not save properly. I did a "save copy as", and after re opening that (saved copy), it allowed me to save as usual. I do not know why, but it helped me.
Best of luck.

Zargg71
Hi. Have you tried save copy as? I had a stubborn old project a few weeks ago that I could not save properly. I did a "save copy as", and after re opening that (saved copy), it allowed me to save as usual. I do not know why, but it helped me.
Best of luck.

thanks for the tip. Sounds like a very good one. I haven't tried "save copy as". in fact I'm not even sure what the purpose of that is, except to maybe fix a corrupt project

"Save Copy As" allows one to save a copy of the current project and continue working with the current project. This differs from "Save As" in that "Save As" immediately changes the currently open project to the "Save As" project.

This has been happening to me a lot lately, across multiple projects in Splat. The play/stop trick does work, but it's very disconcerting. 

Increase the File System I/O to at least 512KB (Preferences->(Advanced Mode at the bottom)->Audio->Sync and Caching), and the problem will go away.  Mettelus suggested this when I had the exact same problem several months ago and it permanently solved it for me.

Interesting fix. It's still a bug no doubt. I have a very fast new computer and there's no reason why I should have to raise those buffers. I don't like the latency I get from doing that.
 
This never happened with my old computer and Win 7 and Plat. It used to happen a lot more when I first got the new  computer in June, likely due to other weird things that were going on.
 
Now it's extremely rare that it happens. And with the new template I built from scratch and my switch to 64 bit Plat I may not get it anymore on new projects.
 
The last one I got it on was a very bloated 32 bit project and it happened several times with that one. It makes sense to raise those buffers on a bloated project. The workaround I prefer is to hit the spacebar 2x (start and stop) then when I hit save it's fine.