I cant open backed up files - Im guessing its EFS? - green files - encrypted?

Cant take ownership.

Whats the chances this is Encryption? From 1 of 10 say?  

(10/10) Green files are encrypted. The keys would have been lost if you did not back them up, when you rebuilt the PC.

"If you did not take the trouble to backup the encryption key then you're stuffed"

I didnt know there were any encrypted files.

For future ref - How do you check if there are any encrypted files on a PC before reinstalling windows?
Aside from ask the user(s)?

 

The method that Microsoft recommends is to use the CIPHER.EXE utility with the /K /N parameters, as in

CIPHER.EXE /K /N

This works at least on Windows XP SP2, but may also be part of earlier versions of Windows as well.  This'll find the files no matter where they are on the drive (at least, so long as you have the ability to read file properties).

Just in case - is it possible you had backed up the user profile (i.e. the folder under C:\documents and Settings)?  If so, then the EFS key recovery software programs that you can find on the 'net might well get the keys you need to decrypt the files.

files used encryption = I was stuffed.  Does anyone have the time to make an image of a disk before erasing? Would have been sweet in this case.  Data wasnt important to client in the end, but Iw as in shock for a while.