failed to open information about volume of archive

Hi. I'm running true image 2013.

I've been merrily making full images of my C drive for a year now - never needing thankfully to restore the images.

Today I need to, and cannot restore any images I've made at all.

Each one says "failed to open information about volume of archive" There's an error code and a link to the archive but that doesn't provide any further info.

Any ideas?

I'm on win 7 sp1.