If you go through the latest bug fix list for X3e it is mentioned there as being resolved.

Oh well...

SOLVED!
 
I had this problem today, in 8.5.  I read somewhere that you should just output an audio file (either of one track or more - doesn't matter).  Once I did that, magically it then allowed me to save the project.  
 
Nothing else I read about and tried worked.
 
 

Do you mean export an audio file or just start playback?

Next time first try deleting the files in your Picture Cache folder, which is usually the problem.

carl
Next time first try deleting the files in your Picture Cache folder, which is usually the problem.

I will try this next time...this has been a periodic problem for me also...several threads on this...x3e seems to have reduced the frequency...but periodic crashes when loading a song I've saved our when I try to work on it still "bug me"...

What is the "picture cache" and why is it important/a problem...?

Vastman

carl
Next time first try deleting the files in your Picture Cache folder, which is usually the problem.

I will try this next time...this has been a periodic problem for me also...several threads on this...x3e seems to have reduced the frequency...but periodic crashes when loading a song I've saved our when I try to work on it still "bug me"...

What is the "picture cache" and why is it important/a problem...?

.WOV files- waveform images displayed with audio clips, files.

Maybe worth mentioning in this context as well:
A HDD needs nearly 10% of it's capacity to remain free in order to work reliably and to be able to perform defragmenting and such. So, even if you have 30 gigas free space, it might not be enough for fluent HDD performance, especially if the HDD is very fragmented. At least this used to be the rule. If this is not true today, the better.

I'm not sure if restore point (Volume Shadow Copies) are reported as disk space used.
You might check the configuration for restore space size.
Personally, I have it set to 0 and I just make frequent image backups.
 
Also, you can run Disk Cleanup on the drive to free stuff that usually is not needed after an installation is solid.