Have exactly the same problem, tried http://support.precisionmanuals.com/kb/a111/aircraft-loads-up-dead-no-activation-window-no-landing-gear-simconnect-issue.aspx no luck.

at the first time I was able to make a flight, second time, the P3D freeze, already opened a support ticket. activation was successfull, and its still activated.

All I had the same problem, I put in a ticket and the following was the guidance to try to get it working.  It worked at least for me, and I followed it to the letter:

 

1. Uninstall the PMDG 747-400 Queen of the Skies II product from Control Panel\Programs & Features.

2. Manually delete the PMDG 747-400 folders (7 of them in this product) in <P3D root folder>\SimObjects\Airplanes folder.

 

3. Manually delete any PMDG folders (13 of them total in this product)  in <P3D root folder>\SimObjects\Misc

3. Manually delete the <P3D root folder>\PMDG\PMDG 747 QOTS II folder.

4. Manually delete the PMDG 747-400 folders (7 of them in this product) in C:\Users\(Your Windows Username)\AppData\Roaming\Lockheed Martin\Prepar3D v3\SimObjects

- You may need to enable the Windows folder option "Show hidden files and folders" to see this location.

 

5. Download a new copy of the installer from your account at the PMDG store, it will contain the absolute latest version.

6. Install the PMDG 747-400 Queen of the Skies II from your new installer.

 

V/R 

Kris