yeah, tb, my bad.

If i's a laptop it's tricky,
But a desktop it's pretty easy to add more storage. 
1 TB Western digital  7200 RPM Blue $54. 
 

Your Recording and Playback I/O buffers effect your DISK %. The lower the settings, the more work is put on your DISK. I suggest raising it and getting at least a 7200 RPM hard drive for audio only.
 
CJ
 

Thanks guys, for all the great info.
So what happens when the meter is in the red?  Is a large project likely to never complete loading?
And just to confirm, if we switch to a SSD drive for the project data drive (.cwp, audio), this will improve performance?
...
I'm using X3Producer, win7 64bit , i7 2.8mHz.

Actually I seem to keep reading that a SSD drive is best for your C drive-- OS and Programs, and a standard SATA 7200 Blue or Black drive for the audio and projects.
SSD drives are pretty small still dollar for dollar so I can see this logic.
I'm still buying 1TB drives as I think they are the best bang for the buck.
Pretty hard to fill them up if it's just Sonar.
Sample Librairies are another kettle of fish but I don't have anything more than what came with Sonar. 

So, did you do any trouble-shooting?
 
Do other projects load?
 
Have you tried opening in safe mode?

Hey, thanks for the suggestions, jm24.  I didn't know about safe mode.  Yes, other projects open.  It's just the last two saves of the one project that won't load.  I wouldn't be surprised if it the biggest project i have ATM.
I'll definitely give safe mode a go, right now.  Is safe mode pretty self explanatory - run and follow the promts?
 
 

So my project opened in safe mode. awesome!  Thanks. jm24.  The only problem is, i selected to load all the plugins, and now it is open, in safe mode, with all the plugins loaded. I'm kinda shaking my head because i don't know what to do next - to be able to open in normal mode next time... what should i do now?  Save this open project as a new file?

 
 

I never use save only save-as to a new name.
 
Do it to a new folder.

OK, copy audio too to new folder when it asks?