I did some testing a while ago with a group of mixed files that included a TON of damaged ones. The majority of the damaged files showed up with a few different tell tale signs:
1. Duration field that was empty, or a very short duration like 0:05 to 0:30.
2. Very strange sample rates.
3. Unusual bit rates. Usually really big like 8000 or more.
By sorting by these columns in file view and then going to the bottom or top of the list, I was able to weed out something like 95% of the bad files in a just a few big chunks. I'm not sure if your bad files will show up like this, but I thought I'd mention it.
Oh one big note: I imported all of these files *knowing* a bunch of them were damaged. I'm guessing that during the import process JRiver did something that made the durations, and other fields show up with strange values, thus cluing me in that the files were probably bad.
Good luck to you.
Brian.