More answers about Installation/Activation (AE) or:
If you are using Articulate Engage 1.x and install Flash Player 10, Engage will prompt you to install Flash Player 6 and then discontinue working.
To fix this problem, download and use the Articulate Updater for Adobe Flash Player 10.
You can learn more about this issue, which also impacts Presenter 5 published output, in this Knowledge Base entry.