Are the files still in the avast chest?
How did you get them out of the chest into c:\virus check\?
Files in the chest are I think encrypted so if you copied them to c:\virus chest\ using explorer they could be encrypted and Jotti won't scan them, perhaps this is why they are reported as 0 bytes, I don't know, I have never heard of this before.
If you have the files in the chest you can restore them using the Chest, Menu, File, Restore, that should put them back where they were originally. Then you could try Jotti again using the original location. Sorry I'm running out of ideas too.