Your computer either does not have the Flash 4 plugin installed or switched on.
The e-cards section of the lennon.net site has to have the Flash 4 plugin to work.

The plugin is free and can be obtained from http://www.macromedia.com/shockwave/download/?P1_Prod_Version=ShockwaveFlash

If you have a PC the download time is approx. 1 minute @ 56K modem as the file size for Flashplayer 5 is 219 K

To check if Flash is switched off in Internet Explorer 5 or 5.5
Got to the menu > Tools > Internet Options
Click on the Security tab, then the Custom Levels button
To turn on Flash, the Run Active X controls and Plugins box should be checked