I am working on building a SharePoint Server 2010 Enterprise environment for Demonstration purposes. I applied my custom branded AdventureWorks master page and created a Search Center sub-site like I always do.
I then uploaded some sample documents and performed a Full Crawl. After the crawl completed I opened the site in my browser and attempted a search for what I knew would return results, only no results were found.
Interestingly enough, I then performed the same query FROM the Search Center site and it found 74 results. Weird, I thought. I then noticed in the query string was: http://AWDemo/searchcenter/pages/Results.aspx?k=sharepoint&cs=This%20Site&u=http%3A%2F%2Fawdemo
The &cs=This%20Site&u=http%3A%2F%2Fawdemo portion of the query string was what concerned me so I went to the Search Settings page and checked my settings.
I had the following settings which I expected would work based on my previous experiences:
Enabled Custom Scopes
Do not show scopes dropdown, and default to contextual scope
Just to test I changed the middle dropdown from Do not show scopes dropdown and default to contextual scope to Do not show scopes dropdown and default to target results page.
I attempted another search from my home page search box and voila, it worked just as I would expect.