Run out of memory with 80% space left on hard drive

Hi!
I did something I don't often do last night and as a result got an error popup.
It said "Could not save entire recording.  System memory could be full".  Something very close to that effect.
 
I have run across it here and there in the X-series.  But not often.
I think it happened because I have 110 tracks, 40% or more of which are archived and not even being used.  A few are midi feeding audio tracks (session drummer, etc).
 
Another thing is that I often do not record audio after being 90% done a mix.  Meaning, there were a lot of frozen tracks and plugins being used.  Especially on a project with 50+ tracks being used at one time.
 
I use X1d 32-bit on Windows 7 64-bit.  16GB RAM (8 used in 32-bit X1d).  C drive is OS/software, D drive is audio.  Both huge and not remotely close to being full.
 
My CPU usage was pretty low, and my disk-usage was I think around 70% when I am doing playback on it.  I have 80% space left on my audio drive.
 
So, has anyone run across this error before, and if so, how do I work around it?

It sounds like the project is too large for 32bit SONAR. It does not matter how large your machine is, running the 32bit version of SONAR imposes 32bit restrictions on the project. The only way to remove those limits is run the 64bit version.

IIRC UAD got their act together on the conversion to 64 bit plugs. There were some minor issues for some users but overall most people did not report issues. The issues I did see reported seemed to have been resolved.
 
Regards,

I would add that there is NO reason you have to remove your 32-bit Sonar install, just because you also install the 64-bit version.
 
LOTS of folks, myself included, keep both 32/64 versions of Sonar installed.  They happily can co-exist on the same computer.
 
This will give you a safety net, so that if you have trouble with any particular project in 64-bit Sonar using 32-bit plugins, you can always use the 32-bit Sonar to get around that set of issues.
 
So, I recommend you keep your 32-bit installed, and simply add a new install of the 64-bit Sonar.
 
Further, since you have a bunch of 32-bit plugins, I would go check to see if the vendor has updated any of those to 64-bit, and for the ones that have not, I would create a new sub-folder within your current 32-bit plugin folder, then test each 32-bit plugin to make sure they work in 64-bit Sonar, and if they do then move them to the new sub-folder.  Add the sub-folder path to 64-bit Sonar in the Cakewalk Plugin Manager.
 
The nice thing about keeping a sub-folder within your existing 32-bit plugin path is that both the 32-bit and the 64-bit Sonars will pick up those plugins.  The 32-bit Sonar will detect the sub-folder, since it is subordinate to the main plugin folder, which is already in its search path.  The 64-bit Sonar will pick up ONLY those 32-bit plugins that have been tested by you to work in 64-bit Sonar.
 
And, you will have only a single copy of the plugins, using the above approach.
 
Bob Bone
 

I would imagine it would yell about missing plugins, but otherwise I think it would work OK.  Others can chime in on this.  I usually leave 32-bit projects to be worked on with 32-bit Sonar, but I do not know if that is a limit I arbitrarily put into place, or not.
 
Bob Bone

This thread keeps on easing my mind :)
Seriously everyone, thank you for your experiences with this.  Learned a lot.

Recording a single audio track (not multi-miced, midi, etc).