I came across this very annoying message when provisioning the SharePoint 2010 Search Service Application recently, and interestingly it occurred on two farms on the same network.  Both were brand new stand-ups a Test and a Production farm.  Both were two-server farms, a SharePoint and  a SQL Server database.  The message appears when you provision the Search Service Application and then navigate to the Search Service Administration page.  The full message is something like:

Crawl: The search service is not able to connect to the machine that hosts the administration component. 
Verify that the administration component c8519b74 status -<GUID> in search application Search Service 
Application is in a good state and try again."

There are numerous blogs relating to this  post but none of them helped me solved the situation.  So I decided to recreate one of the farms.  This is when I came across another problem initially when trying to create the farm in Powershell, I got the error:

“The given key was not present in the dictionary”

when I tried to create the Central Administration Database. When I used a different account the farm created perfectly OK.  I then tried to create some managed accounts.  Through the UI I got the same error again about the ‘the given key’, but with Powershell it was fine.  On Binging the problem I found the following forums thread:

http://social.technet.microsoft.com/Forums/en-US/sharepointadminprevious/thread/5279f8da-2924-461f-8c35-5b81a2329927

and the solution suggested which I have seen on other blogs is as follows:

Try this:

1. Open up “Active Directory Users and Computer”
2. Select “Advanced features” from the “View” menu
3. Right-click the relevant account(s) and select “Properties”
4. Select the “Securities” Tab
5. Scroll down and select “Authenticated users” in the “Group or user names:” field
6. Allow “Read” permissions in the “Permissions for Account Operators” field just below
7. Hit Ok

Sure enough this solved the issue of “The given key was not present in the dictionary”.  I then proceeded to build the rest of the farm, but I still got the original problem of the Search Service being unable to find the administration component.

Eventually I tracked this issue down to there being an installation of IIS 7.5 Express edition having been installed for whatever reason on the SharePoint Server.  Along with this came the .NET 4.0 Client Profile and Extended Profile.  Now I’m unsure exactly which component it was caused the issue, but uninstalling all of then definitely solved the problem on both farms.

So in summary, make sure that IIS 7.5 Express, .NET 4.0 Client Profile and Extended Profile are NOT present on your SharePoint Server when you install.

Hope this helps

Cheers

Dave Mc