I logged into the computer to type an edit to the above post, but you already read the original.
 
If it is V-Vocal in the project file, an option would be to copy the project to a new directory, but NOT copy over the last wav files you edited (leave those in the original location). SONAR will then tell you that you have missing audio, but do not find them... If SONAR doesn't load a wav to process against, the V-Vocal data might strip off, then you can save the project with a new name and import to original wav file (if that works).

Cool! Will give it a shot, thanks :)

Nah! didn't work :/ damn it! I have a feeling it is a corrupt song file..

There's a possibility it could be plugin issue. I've heard of reports of Sonar losing plugin settings - maybe it's corrupting them in this case and crashing it.
 
It's a long shot (and probably a huge PITA), but what you could try is rename your plugin directories and do a re-scan to effectively remove your plugins, then load your project.
 
If your project loads, then you know it's one of the plugins that is causing the issue.
 
The time consuming part will be copying each plugin DLL back one by one to isolate the one that is causing the issue (note however, that there's a chance that it maybe affecting more then one plugin if it is a corruption issue, so make sure you've nailed down all the problem ones).
 

Actually on second thoughts, just using Sonar's plugin manager to disable plugins might be easier than renaming directories.
 
It'll be much easier to add them back in as well.

Have you tried turning off 64-bit double precision?

Hi
Not sure if this would work, but maybe worth a try:-
 
Copy the project folder and paste it back with a new name e.g. "safe-backup" (this will prevent any accidental harm happening to your original)
Create a new project (with a new name) eg "myamazingsongrecovery.cpl"
Import the audio tracks one at a time (from the copy you just made eg "safe-backup") and test by playing to the end before importing the next audio track, hopefuly everything will work, if not, you may be able to identify a bad audio file if there is one.

msmcleod
Actually on second thoughts, just using Sonar's plugin manager to disable plugins might be easier than renaming directories.
 
It'll be much easier to add them back in as well.

Yip, tried everything with the plug-ins. Safe mode, disable on start, removed directories and used only one basic. Still happening :/
Thanks though...

sharke
Have you tried turning off 64-bit double precision?

Thanks...Just tried it but still no joy :/

jumpeyspyder-
Hi
Not sure if this would work, but maybe worth a try:-
 
Copy the project folder and paste it back with a new name e.g. "safe-backup" (this will prevent any accidental harm happening to your original)
Create a new project (with a new name) eg "myamazingsongrecovery.cpl"
Import the audio tracks one at a time (from the copy you just made eg "safe-backup") and test by playing to the end before importing the next audio track, hopefuly everything will work, if not, you may be able to identify a bad audio file if there is one.

Thanks. I started doing this last night. It seems to work so far but I have 30 tracks and hundreds of audio files (loadsa plugs) so it's one damn arduous task that is the final option I will try once I've exhausted all other possibilities. When I worked on the song the other day I simply removed some old vocals on one track and re-did them. I also used v-vocal to clean them up and bounced them. I added a new track for an extra small vocal part,  tweaked the mix, bounced one or two other wavs and then I used Limiter 6 to master. Up until that point and a few days prior, I could go into the project no problems. I'm left with a juicy rendered wav and mp3s which is something but yea, I'd love to just be able to get back to the project and work a little more on it and also make an instrumental version. Grrrr! I should have backed up!