Access denied when crawling MOSS Content

The SharePoint search is configured properly and everything is running perfectly. My SharePoint web applications use Kerberos authentication. I applied .NET 3.5 SP1 and the search didn’t work. I got the following error:

Access is denied. Verify that either the Default Content Access Account has access to this repository, or add a crawl rule to crawl this repository. If the repository being crawled is a SharePoint repository, verify that the account you are using has "Full Read" permissions on the SharePoint Web Application being crawled. (The item was deleted because it was either not found or the crawler was denied access to it.)

Lots of blogs talked about this issue. The suggested solution is below:

Disable the loopback check

Follow these steps:
1. Click Start, click Run, type regedit, and then click OK.
2. In Registry Editor, locate and then click the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Right-click Lsa, point to New, and then click DWORD Value.
4. Type DisableLoopbackCheck, and then press ENTER.
5. Right-click DisableLoopbackCheck, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Quit Registry Editor, and then restart your computer.

Source: http://support.microsoft.com/kb/896861

This resolved the issue in my production but not QA!

So what’s the difference between my production and QA?

After one day investigation, I found there was a wrong Kerberos setting in QA. Run the following:

Setspn –l severname

I found there was a line like this: HTTP/servername:portnumber other than HTTP/servername. So I run setspn –d HTTP/servername:portnumber SharePointServiceAccount to remove it, did a search again and it worked!