The "Out of memory" problem can also be caused by 32 bit plugins using large sample libraries.
The 32 bit plugs, being bridged, are limited in memory usage.  Not saying this a problem for you,
just that it can cause the condition.

Cheers!

Are you using any mp3 files for samples ?

Cheers,
Jerry

Today...
I bounced all the files to new audio tracks. Got rid of the old ones. Checked the .cwp file size and it went from 2.81mb to 506 Kb. Huge decrease in file size. I kept all the other versions of the file so I could go back and find the reason as I would not like to get in this situation again.
To answer other question here, no mp3's were injured in the making of this project, no 32 bit plugins, and I did not have a chance to check the resource monitor yet. Funny note, as I was going to do just that, I was going to close the program and as it was saving - the screen went white and did the no responding hand to the face. It's been 15 minutes now and still not responding. No worries though, as I had already saved the file.
Resouce monitor shows the following:
SONARPDR.exe is using 675,312 kb of memory at present
10gb free out of 16gb
All four cores are spiking up down up down up down - sharks teeth!
I picked a great day to go swimming...

Is there antivirus software running, by chance?
 
And, is it possible some other background task has kicked off?
 
What does DPC Latency Checker and/or LatencyMon think of your system's ability to handle audio streaming, with Sonar not running?
 
Is it possible that this particular project got corrupted somehow?  Can you rebuild it in a new project, since you have bounced all the audio?
 
Bob Bone
 

I assume you ran Windows Task Manager to check on memory usage.  I agree that anti-virus software can be horrible.  I use Microsoft Security Essentials because I found some other programs (like Norton) to be as bad as the malware itself on performance.
 
I really hope you are running MS Security Essentials or Webroot to clean out spyware.  To me, your symptoms sound like spyware grabbing system resources.
 
In my case (12GBs RAM), large sample libraries have more of a problem with disk performance than with memory, so I hope your system is clean of spyware.  I could be wrong, but it would sure be worth checking.
 
Take care, and I hope all turns out well.

Yes, there's definitely something funny going on here...

With your specs you shouldn't have this kind of issue...

Have you filed an Issue Report with Cakewalk???

I saw a different older thread that talked about some memory setting in each instance of something I think was called Softune EVO, and that in that particular case this guy had jacked up some memory setting to something quite high, then had a BUNCH if instances loaded, and that ran him out of memory.
 
What sort of plugins are loaded up in this project?  Can you list them please?
 
Bob Bone