Why am I getting ERROR_INVALID_FUNCTION – 0x80070001 trying to play back MPEG files?
WMP uses DirectShow for MPEG playback, and a number of third party applications install MPEG DirectShow filters that override the MPEG filter WMP normally uses. In particular, people sometimes seem to have conflicts with Intervideo WinDVD, Ligos, Micron WinDVD, System Shock (LGVid.ax is the key file here, TMK), and Creative Encore DVD. Uninstalling that software and potentially reinstalling WMP should fix the issue. There’s an article about the problems with WinDVD here. If you need to turn off a 3rd party MPEG codec and don’t know how to uninstall it, the Radlight tool is what you need then. Or the DirectShow Filter Manager should work. In some cases, the video card driver’s video overlay may not be working properly follow the steps here to work around that driver bug. Note that mcspmpeg.ax is a MainConcept MPEG file installed by a number of MPEG editing tools. It can cause crashing errors in playback. Most notably it’s been known to make it so that you can’t click on an Internet link
