Are the RAW files on your hard drive, in a card reader or are you attempting to view them while the camera is connected to your computer by usb cable?
Update to issue.
Seems .CR2 files from my 7d are fine. I'm able to view and edit them in DPP. I hook the USB cable up for that.
Seems that .CR2 files from my S95 using an sdhc card is where I'm having a problem.
I can't view thumbnails in DPP but thumbnails are there in Zoombrowser.
.JPEG's are fine
Hopefully I'll be able to recover some keepers that I really wanted to share.