Why is my Firefox browser trying to open Windows Media Player when it starts?

[davidm]

This has been happening over the last couple of days. Every time I start up Firefox it brings up an alert window with the following message:

Windows Media Player

The file your are attempting to play has an extension (.) that does not match the file format. Playing the file may result in unexpected behavior.

Do you want the Player to try to play this content?

I click No, it closes, and I can then use Firefox with no problem.

It appears that Media Player is trying to open some file that does not have a file extension. It shouldn't be trying to open anything!

Why would Firefox try to open Media Player on start up?

[Whack-a-Mole]

What is the default homepage it tries to go to upon starting?

Perhaps something on that page is trying to get media player to run.

You could also try re-installing Firefox. It is a small download and quick to do. This may reset something that got goofed up.

Third, consider running a virus scan. It is possible something is trying to hijack your browser (or has hijacked your DNS).

[davidm]

I use the Session Manager add-on, so when I open Firefox, before the browser comes up I see a Session Manager screen that allows me to choose between saved and previous sessions. The alert window comes up simultaneous to this screen so the browser isn't (or at least shouldn't be) trying to open any pages yet.

My home page is www.google.com but, as I say, this happens before it gets to the point of opening the home page.

I'm currently running a virus scan since I'm concerned that might be the problem.

[BigT]

Try opening Firefox in safe mode. That should be an option in the start menu folder.

If it stops the problem, then you can start in safe mode again, and choose disable all plugins, which will then let you add them back in one at a time to see if one of them is causing the problem.

And if you want more help, a list of your plugins might be useful.

Oh, and make sure that your Tools > Options > Applications doesn't include anything that could start WMP. The only things that should mention it at all should be referring to the Windows Media Player plugin. And I guess also make sure your Internet shortcut is only pointing to firefox.exe.

[davidm]

I found out what's causing it, though I'm not sure why.

If I disable the plugin called "Windows Media Player Plug-in Dynamic Link Library" it no longer happens.

I'll have to research that plugin.