Check to ensure you're trying to run the right product for the license you have.

From the menu, select 'Houdini Core' to run Houdini Core, 'Houdini FX' to run Houdini FX, and 'Houdini' to run the program you have licenses for, searching for a Houdini FX license first and then Houdini Core..

From the command-line, type 'houdinicore' to run Houdini Core, 'houdinifx' to run Houdini FX, and 'houdini' to run the program that you have licenses for.

For more licensing help please see the License Trouble FAQ.