Image Backup Fails! Options?

Any thoughts would be appreciated. My Windows 7 image backup on my VPCZ1 (ssd version, which I REALLY like) fails, with the error:

"The volume does not contain a recognized file system. Please make sure that all required file system drivers are loaded and that the volume is not corrupted. (0x800703ED)."

The main partition has been checked and rechecked (chkdsk, etc.) and shows fine. Disk Manager shows that partition, as well as the Recovery and "other" partitions as being healthy. I have also checked the target drive and even tried a different target drive.

Initially, I was trying to backup to an encrypted drive, and got different errors. So I decrypted it back to normal, and get this one.

I had done a restore a few weeks ago from a may 2011 image backup (joy of joys) and have everything reinstalled, patched and updated, and just wanted to make a more recent backup. AV software is all disabled, as well as anything else I can think of that might interfere with this. The error message pops up within about 2 seconds of starting the backup, after source and target have been selected and accepted.

I have searched for 2 days, and all I can find are how to restore systems when you get this error. I can't even tell which drive or partition is causing it the heartburn. It indicates (and gives me no choice on this) that it is going to backup the "System Reserved (System) ", "C: (System)" and "Unnamed drive (System"). I have nothing to hang my hat on, but it feels like it is one of the two hidden system drives that is not happy. Unfortunately, not sure how to look at those, much less safely "repair" them without a good image backup handy. Catch 22.

Nothing in the event logs. Am trying to backup to a large (2TB) external USB drive which also checks out OK. Standard backups work fine for that one. Images are the issue.

Any thoughts or pointers would be appreciated. Not a novice at this, but there is always something....

Thanks! -Mike

VPCZ1 i7 250SSD 8G RAM, etc...