Recently Microsoft lost a patent judgement, which resulted in them pushing down an “update” to IE that forces you to click on any embedded object to “activate” it.
Embedded objects can be flash movies, video clips, audio, etc.
This is really bad for sites that use flash. Things like navigation and rollovers don’t work until you first click on them.
This article talks about the work around, and how you can incorporate this into your ASP.NET projects.
http://www.codeproject.com/aspnet/IEActiveXActivation.asp