Using WMP 11.xxx, and have installed Essentials codec pack ... this on two computers.
On one computer (desktop) using an external hard drive with a movie on it I can click the VTS files and it will automatically open WMP and start playing the video.
On a laptop, the same procedure opens WMP, but it then just sits with a blank screen doing nothing. However, if I go to File and select the VTS file/s, they start playing.
I've double-checked that the two systems parallel each other, and reinstalled codecs etc.
R.