The Pension Planner is designed to run with Flash version 7 and above.
If you don't have Flash, or you have an earlier version, you will automatically be prompted to access Pension Planner in another format.
When prompted, you should click the "Start Pension Planner" link. You will see something similar to the following:

Just click "Run" or "Open" and follow the instructions on screen to install Flash on your PC.