By now, everybody should have heard that Flash content needs to be activated before using it on Internet Explorer (5.x upwards)
Adobe just released a nice extension that does a workaround for everyone which doesn’t want to touch the code
Microsoft recently released an update to Internet Explorer that changes how Internet Explorer handles some web pages that use interactive controls. Interactive controls are ActiveX controls that provide user interfaces. When a web page uses the APPLET, EMBED, or OBJECT elements to load an ActiveX control, the control’s user interface is blocked until the user activates it. If a page uses these elements to load multiple controls, each interactive control must be individually activated. For this reason, certain web pages, including the default Flash Player web page, may require users to manually activate ActiveX controls by clicking on the control or using the TAB and ENTER keys.
For more information on this change, please see Microsoft’s Activating ActiveX Controls.
To eliminate the need to first activate the Flash Player so users can interact with Flash content, Adobe has created the Flash Active Content Update extension, which installs two HTML templates that Flash authors can use to embed their Flash SWF files. Using these templates, embedded SWF files will activate seamlessly without the need for an additional mouse click or other user activation.
The .mxp extension can be downloaded here:
http://www.macromedia.com/support/flash/downloads.html#flash8
Happy fixing 
The Flash 8 and IE (update) by Tiago's Weblog, unless otherwise expressly stated, is licensed under a Creative Commons Attribution 2.5 Switzerland License.
