http://support.quickbooks.intuit.com/support/Pages/KnowledgeBaseArticle/1009649

Overview
Step 1 of 3: Reset the entitlement data file
Detailed Instructions
Note: The entitlement data file is stored in a hidden Windows folder. You can still view the folder’s contents if you open it directly using the instructions below. However, if you prefer browsing to the folder, you must first configure Windows Explorer to display hidden files and folders. For more information, step 1 in “Searching for a file on a computer running Microsoft Windows” instructs you how to display hidden files and folders.

Follow the instructions for your operating system and version of QuickBooks:

  • Windows 7 or Windows Vista:
    1. Click the Windows Logo button.
    2. Copy the bold text below for your version of QuickBooks and paste it (or type it) in the Start Search field. Then press Enter:
      • QuickBooks 2010 or Enterprise Solutions 10.0:C:\ProgramData\Intuit\Entitlement Client\v5
      • QuickBooks 2009 or Enterprise Solutions 9.0:C:\ProgramData\Intuit\Entitlement Client\v5
      • QuickBooks 2008 or Enterprise Solutions 8.0:C:\ProgramData\Intuit\Entitlement Client\v5
      • QuickBooks 2007 or Enterprise Solutions 7.0:C:\ProgramData\Intuit\Entitlement Client\v3
    3. Right-click the EntitlementDataStore.ecml file and select Delete. Click Yes to confirm you want to delete the file.
    4. Open QuickBooks, open your company file, and follow the instructions to register the application. If you can’t do that, then this solution step did not resolve your issue. Close this window and proceed with the next solution step.
  • Windows XP:
    1. Click the Windows Start button and select Run.
    2. Copy the bold text below for your version of QuickBooks and paste it (or type it) in the Open field of the Run window. Then click OK:
      • QuickBooks 2010 or Enterprise Solutions 10.0:C:\Documents and Settings\All Users\Application Data\Intuit\Entitlement Client\v5
      • QuickBooks 2009 or Enterprise Solutions 9.0:C:\Documents and Settings\All Users\Application Data\Intuit\Entitlement Client\v5
      • QuickBooks 2008 or Enterprise Solutions 8.0:C:\Documents and Settings\All Users\Application Data\Intuit\Entitlement Client\v5
      • QuickBooks 2007 or Enterprise Solutions 7.0:C:\Documents and Settings\All Users\Application Data\Intuit\Entitlement Client\v3
      • QuickBooks 2006 or Enterprise Solutions 6.0:C:\Documents and Settings\All Users\Application Data\Intuit\Entitlement Client v2
      • QuickBooks 2005 or Enterprise Solutions 5.0:C:\Documents and Settings\All Users\Application Data\Intuit\Entitlement Client
    3. Right-click the EntitlementDataStore.ecml file and select Delete. Click Yes to confirm you want to delete the file.
    4. Open QuickBooks, open your company file, and follow the instructions to register the application. If you can’t do that, then this solution step did not resolve your issue. Close this window and proceed with the next solution step.