Well, I'm not all that convinced that this will help, but I'll throw out a suggestion.
Boot with the apple-s (single user mode) and run fsck -y. If you get errors, the disk check will try to fix them. If you see errors, run fsck -y again & again (unless it's the same error being reported). Then boot and try to run the keychain program again.
I know this is a long shot, but some of the older machines in my lab have been fixed with this procedure when applications wouldn't run (unexpectedly quit).
Good luck.