Windows 7 - Xbox 360 / Windows 7 / Media Center Extender - media sharing not worki

As I'm clicking "Play To - Xbox Media Center Extender" on my Windows 7 Laptop, I'm getting an error message of my Xbox 360/TV screen that says...

"Windows Media Center cannot find the specified file. Be sure the path is typed correctly. If it is, the file does not exist at the specified location, or the computer where the file is stored is offline."

therefore, not allowing me to watch any video files (movies) any longer. I never had this problem before and everything has always worked fine. I use to use .mp4 files, and without changing anything, it stopped working. I then went on Xbox.com and read their Q&A, and didn't see .mp4 being allowed anymore for whatever reason, but saw that .wmv is allowed, so I converted all of my files to .wmv, to no avail. I've been trying to figure this out by myself for the past 3 days, and I've tried everything, and am getting really frustrated now. That's why I came here and hoped someone knew how I can resolve this and get everything working again.

I should mention that before I was getting this error message, I was getting another error message that said..

"Cannot Play Video
The file type is not recognized and cannot be played. Either the correct codec (a file that compresses/decompresses audio or video) is not installed or the file is corrupt."

I don't know why the error messages changed, but still, same thing.

Note: that directly in Windows 7 it is working file.

On Xbox360, I am only able to watch Pictures. The Songs and Videos, I can't.

Thanks for submitting a fix.

I renamed my User name from "Sébastien" to "Sebastien" and it worked!

I am having the same problem, is there really a fix that works