A few months ago I noticed that streaming video (from ASX files) stopped working on my website when I viewed them from Internet Explorer 7 on Windows Vista. Every time I clicked the play button for an embedded video, it would say "connecting” but then nothing would happen—no video played. At first I assumed that it was due to a Windows Update. But after viewing the same pages correctly from another machine using Vista (the video worked on that machine), I decided the issue was something stranger. In fact, I found that the issue was quite bizarre:

1. I could view the same pages fine with Firefox on Vista using Windows Media Player 11.
2. I could view the streaming video from Windows Media Player by accessing the ASX URL directly in Windows Media Player.
3. The issue was affecting this machine with all websites that had embedded video—not just ASX files.
4. Streaming audio was still working as expected.

I could find no answers online. Many articles on the internet pointed in the direction of a missing or corrupted video codec. But since the videos played fine in Firefox and via Windows Media Player directly, I decided to look elsewhere.

In the end, I found a solution to my problem. For some reason, Internet Explorer stopped allowing embedded video in WMP (Windows Media Player) unless I was running IE as Administrator. To do this, I right-clicked the shortcut to launch the program and clicked "Run As Administrator”. All of a sudden I could play video in IE7. But this solution was slightly annoying since I had to remember to do that every time I opened a new browser session.

The long-term solution was to turn off UAC (a Vista security feature called User Account Control). While I did not necessarily want to turn UAC off, I found it was most convenient to take this measure. (I discovered this, incidentally, while researching solutions to problems with Valve's Source SDK software and using studiomdl.exe).

I still do not know what happened on this specific machine to cause the issue to begin with. I have a gut feeling it was caused by the installation of some Windows Media Player visualizations that I downloaded from links on the WMP website. I have tried to un-install the visualizations in question, but have not yet found a way to do that.

How to Turn Off UAC

To turn off User Account Control, you will have to be logged in as an administrator. Then click Start > Control Panel > User Accounts. There you will find a link that says "Turn User Account Control on or off". Click that link. To turn UAC off, uncheck the checkbox and click OK. Check the box and hit OK if you want to turn UAC back on.

Note that turning off UAC is not recommended by Microsoft, but it will stop you from getting confirmation pop-ups every time you try to run many programs as well as solve the issue above.

Resourceful Links

• Understanding User Account Control in Windows Vista
• Microsoft Technet: User Account Control
• Accessible UAC Prompts

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2011-11-11 It's been a few years since I wrote this article. I no longer disable UAC. I simply feel more comofrtable keeping it on.