jatoth
Noel,
The issue I tried to describe is not saving the same project as it was many times.
It is when I add tracks/synths/plugs save as then delete tracks/synths/plugs and save as again.
After I delete tracks/synths/plugs and save as a new project file, the file size does not go down.
The space for the deleted items is not released. If you do this many times, the file just keeps growing.

 
Are you sure that you are deleting the synth itself from the synth rack? Deleting the tracks wont release much since the main storage is the synth itself. Its very unlikely that the synths are not released if you delete from the synth rack. Please verify that they are really deleted.
 

Cactus Music
I'm I missing something or would not  a project that was originally midi and soft synths that was bounced to audio certainly become larger. Audio tracks are what takes up data size. 
A midi only CWP file will not be very large. 
As far as I can tell if you "save as" to a new folder location and tell it to "copy audio"  it will leave old audio files behind in the old location.
If you just "save as" in the same folder, the old unused auido is still there. 

The cwp doesn't actually contain audio, but pointers to the audio files. The cwp does, however, contain the MIDI data. Noel would have to give the definitive "what's in there," but the cwp will also contain unbounced Melodyne information (and I also believe AudioSnap info, but not sure).
 
I remember testing the Melodyne in X3 and the cwp got rather large, and even deleting all of the temp files from the Celemony folder, it was all recreated when the cwp was opened (and was actually a noticeable delay during that recreation).

I have been testing out a lot of old projects that were originally created in Sonar 7. I still have Sonar 7 installed alongside X2 and X3. Many of these projects appear to work ok at first when opened in X3 (or X2), but hang after a couple of playbacks or after doing a few small edits. But then on re-opening them in Sonar 7 they appear to be stable there.
 
Some plugins have been updated since the projects were created, but this should not be an issue. All these 3 versions of Sonar are currently accessing the same plugins.

64-bit v 32-bit is not a factor here. The projects that were created in 32-bit Sonar 7 are being access in 32-bit Sonar X3. Bitbridge is therefore not a factor either.

I have projects dating back to the Pro Audio/Home Studio days, and if anything they seem to be more stable than the newer ones, perhaps because I used fewer plugins back then.

On many older projects (maybe X1 or X2) I have the following issue: the projects load but won't play. I click on play and nothing happens. The solution: copy and paste all the tracks into a SONAR Platinum project. Then you have to take time to configure the synths, etc. Very strange.

Noel Borthwick [Cakewalk]
Bitbridge is a sandbox albeit only for 32 bit plugins.

 Noel, that's interesting, but it doesn't help me to understand why, whenever I get a Bitbridge crash (which I assume is what has happened when Windows throws a "Teleport Server has blaah, blaah" message) I find that Sonarplt.exe is "stuck" and typically unkillable, no option to "save the project" is offered and my (Roland) USB audio interface is out for the count and has to be coaxed back into life. Or I can reboot Windows. None of that is what a mere layman understands by the term "sandboxed".
 
BTW, I am not blaming Sonar for the original crash, which will inevitably turn out to be caused by the presence of an outdated or out-of-kilter installation of a plug-in in an older project. I'm just curious to know why the consequences are typically so "game over".

Anderton

mettelus
I am not sure if this will help or has validity...This may be overkill, but the "save as..." is definitely recommended so that the original cwp is left as it was (and be opened in the version it was created in just in case).

 
This is SUPER valid and helpful advice. I've been doing what I do for a long time, and have gone through multiple versions of multiple types of software. As a result I've encountered what the OP has encountered in numerous programs, and your advice can solve many issues.

To this I'd like to add, I frequently find when I go to open an older project, if I hold the SHIFT key down, and select LOAD ALL, it still somehow cleans things up a bit resulting in more success opening older projects.

ebibault51
On many older projects (maybe X1 or X2) I have the following issue: the projects load but won't play. I click on play and nothing happens. The solution: copy and paste all the tracks into a SONAR Platinum project. Then you have to take time to configure the synths, etc. Very strange.

 
If you have changed hardware since you last worked on the project, check that the Master bus output is not set to "None".

Every time that I've had a problem with Sonar opening an older project, I've been able to trace it to plugins that were behaving badly or outdated.  There are a few culprits (e.g., Tone2, SpectrumWorx, Eiosis) that I used frequently in Sonar 6-X2 that will either cause a crash or not allow playback, until I find, remove, and reinstantiate the plugin(s).

Typically the issues I've had with older projects reside with the older plugins.
Within the last couple of months I've began working on a project that was started on Sonar5.
It's mostly audio & plugins (no VSTi's).  I didn't want any hassles so I copied all of the audio to a new project template.  I figure I can easily (and quickly) take advantage of the newest features from SPLAT.
So far, the project has been smooth sailing.  No quirks (knock on wood). 
Next weekend, we'll continue with recording more vocals (to get the songs up to current). 
As smoothly as SPLAT has been running for me over the last year, I don't anticipate any hiccups.
 
Also, most of my "older" projects were saved as .bun files.  It was my main way of archiving back then.
Haven't had one since issue with any of them.  Not even the ones from other studios I worked with back then.