While Testing Search Configuration in SharePoint 13 I was unable to start the crawler as well as Search Application Topology was showing error that it has not been enabled. After a bit of binging find out a Forum Answer by Microsoft Search Product team. Solution is simple install these 4 hotfixes on your Search Server.
For Detailed Information about error and Microsoft Reply.
for Quick Fix:
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http://www.microsoft.com/en-us/download/details.aspx?id=27060
Source: Paul Stork Answer