Trying to get the search service to complete a Crawl of the local SharePoint sites, I was receiving "Access is denied. Check that the Default Content Access Account has access to this content, or add a crawl rule to crawl this content."
After validating that the account had access to the content (sites), and verifying that there were no crawl rules, I eventually expected to find the answer in the event log.
In the event log, there were no entries like the expected "Login failed for user 'NT AUTHORITY\NETWORK SERVICE'. [CLIENT:
As an additional check, I set up the crawler service to run against another SharePoint server, using the same crawl account credentials. Worked fine without a problem.
After checking around, I ran across this post on Microsoft TechNet Forums: http://social.technet.microsoft.com/forums/en-US/sharepointsearch/thread/84f93fbe-f4a6-4683-b25b-b595b9006ad7/
Within the post, someone recommends re-entering the crawler account credentials. I re-entered the credentials, and initiated a full site crawl. The error still occurred, with the same message.
After reading further into others that had encountered this problem, it would appear that the Loopback check security feature is back in Server 2008. After running the work-around http://support.microsoft.com/kb/896861 (see Method 1: Disable the loopback check), and restarting the machine the site can now be crawled.