I just had the same fatal DB error, went to copy the folder contents and the blkindex.dat would not copy over, said I/O error. I downloaded the new 0.8.0, and ran it, receiving the same error. I then deleted the blkindex.dat and reran the installer, it re-indexed the blocks and finished downloading the remaining ones in 75 minutes. My p2pool transactions were missing for a while, it found those as well. Hope this helps someone.
cheers.
cheers.
There is no need to "copy over" anything. You just close Bitcoin (likely the cause of some problems), and install the new version.
