I just ran a check on my hard disk using Norton Disk Doctor 4.03, and it reported damaged resource forks to a whole bunch of files that appeared to be Sherlock plugins. So I tried using Sherlock, but it works fine.
Since it seems like there isn't really a problem, could it be that NDD just isn't recognizing the files and reporting an error? I recently upgraded to system 8.6, and didn't have the problem before this.