Access is denied when I schedule content crawling

I worked on the search crawling schedule in a server farm and received an error message like:

Access is denied (Exception from HRESULT:....)

However, I was able to start a manual content crawling without difficulties. So what happened?

Microsoft has a KB article to explain this situation and the link is:
http://support.microsoft.com/kb/926959. I was glad to find out a solution so quick. But then I wondered, which server I should apply this change to?

Since the environment I deployed has separated front-ends, index and query servers and this article and other web site did not give me clear direction.

After I analyzed the situation and found out I should apply this to the index server, since index server is the one performing this scheduled task.

I followed the KB article and made changes to the index server, everything worked as it should be.

Perhaps next time when we publish some thoughts or instructions and we are using a server farm, includes which server we apply changes to fix the problems may be very help.

Just a thought.