I've seen this happen a few times, but not frequently. I can only imagine it's a Windows issue, but I'm putting this out there in case others might know possible causes:
 
I have two sessions open, one active/highlighted, and the other, dormant. I typically mix on one session, save all the separate PC's and other settings, then manually and visually copy that mix to another project as a reference point (which is the exact same recording session, btw, just a different song). While I'm listening to one of the projects, if I close the dormant project, Sonar sometimes hangs with a White-screen.
 
Normally, I'm in good practice of stopping the transport before doing something like that, but X2a's transport isn't exactly the most responsive. So, in this case, I clicked Stop, but apparently, Sonar didn't register that and I simply broke my habit by going ahead with closing the dormant project. As a result, White-screen. No saving or auto-save was involved, but perhaps a fault on closing the file, or even a Windows I/O error from drive contention because the other file was playing still.
 
Has anyone else seen an issue like this?

I'm getting the white screen when loading a project.
 
Audio/ASIO Driver Buffers are set high (Lynx drivers), etc...
 
I think that Cakewalk/Sonar is not reporting what it's doing fast enough to Windows and Windows freaks out.
(Sort of like a woman I know...) :J
 
Give it time and Windows recovers - every time.
(Sort of like a woman I know...) :J
 
I'm at a loss, so I'm bumping your post in hopes someone has figured this out.
 
Cheers!

Nah, I doubt anyone else has seen this, who knows the problem, but I can work around it. Love the Fat-Head mic-eyes, btw. I have that same kit. Or, at least the Fat-Head I kit.