This problem appears to be caused by Installshield. To resolve this problem, please do the following -
- Open up My Computer
- Navigate to: C:\Program Files\Common Files
- Cut out the Installshield folder and paste into temporary location.
- Install Stronghold 2 as normal. You may want to try running the Setup.exe directly from the CD/DVD.
- After the game is installed. Paste the Installshield folder back into: C:\Program Files\Common Files
- Also clear out the Windows temp folder. Usually located under: C:\Windows\Temp