And the first "TIP" window that comes up in X3 tells you to save CWB
But Let it be known, CWB is not reliable like it once was.

Did you know that SONAR allows you to choose several file
types when saving projects?
CWP Files - A CWP file contains MIDI dad, project-specific
settings, and reference to all audio data that resides in another
location - the current Data Directory which is set in SONAR'
Options, Audio, Advanced Tab

CWB Files - Bundle files contain all the data in a .CWP file in
addition to storing the actual audio data used in this project
 
 
There should be a WARNING that the CWB Files have been known to have problems since SONAR 4
and you should always backup with other methods as well. Such as copying your Per Project Folder.
And save as .OMF

Cakewalk's NATIVE file system saving file "CWB"  has serious issues now, loss in your audio data.
I am one of the unfortunate registered users that has experienced this with a paid client with a deadline
and band members from 2 different countries! And SONAR tech support did not bother to respond still after 2 weeks.

I don't think you can bundle up a file that contains any active Audio Snap processing. From memory you get an explanatory message when trying to create a bundle.

just yesterday i tried opening up a couple .cwb files from 2007 & both would not open due to being corrupted.  this has happened to me numerous times. the "remedy" (opening in safe mode) is a joke because nothing opens, just a blank project.  cakewalk should do something about this: either write a utility program that fixes this, or start a service where someone will uncorrupt the .cwb

wetdentist
just yesterday i tried opening up a couple .cwb files from 2007 & both would not open due to being corrupted.  this has happened to me numerous times. the "remedy" (opening in safe mode) is a joke because nothing opens, just a blank project.  cakewalk should do something about this: either write a utility program that fixes this, or start a service where someone will uncorrupt the .cwb

Did you open them in the same Sonar that created them or in a newer version? Was it created in 32 bit and opened in 64 bit? Just curious.

@wetdentist: Did these files open before? Did you check them after you created them?

And I have been hearing about corrupted bun files before Sonar4. It didn't start then.

No probs with CWB's here. Been using them since the X series but I also export the individual .WAV files as yet another back up and safety measure to be on the safe side. I also back up to 3 different places. Internal drive dedicated for back ups, External drive and DVD. I'm not paranoid. Lol.

"Digital data is not real unless it exists in at least two places"
 
Those used to be my "words to live by," but now it's two hard drives, a Blu-Ray or DVD optical disc, and a separate backup for all three that consists only of rendered WAV files so they can be brought into any project.
 
For really important projects, on-site backup is important as well. The cloud is good for this.
 
Bundle files existed before Sonar offered the per-project saving option, which is waaaaaay better than the days of dumping all the audio in a single folder and having projects point to that audio. Technology has changed a lot since the bundle file was introduced. I don't use bundle files, but not because I've had problems with them; I haven't. It just doesn't seem optimal to save everything in one huge file where if one bit is missing, you're hosed. I've downloaded plenty of zip files from the net that won't open because they became corrupted during the transfer, which seems like the one-size-fits-all file format is trying to tell me something...

What I'd also like to know is whether anyone who saved a bundle filed opened it immediately after saving to see if it loaded properly or not. If not, then it would seem like a good idea to save using a different format. If so, then what about a bundle file "aging" would cause it to become corrupt over time? I know hard drives block off bad sectors, and sectors can go bad over time...could that be part of it? Do bundles saved to flash drives fare any better? What about optical drives?
 
FWIW whenever I save something with any program I always try loading it before shutting down the program, just to make sure.
 
We have plenty of anecdotal evidence that some people have problems with bundle files, but the circumstances under which any problems happen haven't been very explicit...they generally go along the lines of "I saved a bundle file years ago, I tried to open it recently, it doesn't open." Some more data might help narrow down a possible failure mode.

I guess the problem is those who have been having issues never get back to the forum with any follow up, I dug through a bunch of threads on the topic and every single one had the same ending, the regulars asking more questions and the OP disappears into the ozone. 
That is one reason I started this thread. So we are still waiting to hear back from anyone who figured this mystery out. 
 
My feeling is this is not a case of anything going wrong with a hard drive or whatever, It seems to point at the files might just be corrupted the instant they were created. 
The other unanswered question is whether this is a change in audio format issue. After all the message they get is the audio is corrupted. Or is it a change in OS, or a change in Sonar version, 32 bit or 64 bit???? 
 
And is Cakewalk going to keep that outdated knowledge base article recommending bundles I copied to my opening post? I will certainly continue to advise not to use them without a CWP backup alternative. . 

On the occasions when I've used bundle files, I've always treated them like any archiving software. ie create the bundle and before moving or sending it somewhere I ALWAYS open it to check the archiving process worked properly. If it checks out OK then I can use it if not on the occasion is where there's been a problem usually doing it again has resolved whatever the original failure was. Have to admit I've had that occur probably as frequently as any archiving attempts with zip, rar or other earlier windows archiving utilities. That means occasionally I've had a failure. The advantage of zip and rar archives is that there are utilities available that let you examine the archive and often you can salvage many of the files