I get this when I try to run Movie Maker:

My system has Windows 7 SP1, 16GB RAM, 518GB free on the hard drive, running at 1600x900 resolution, 3rd generation Intel Core i7 processor. The device manager searched for new video drivers and said I have the latest for Intel HD Graphics 4000 (driver version 9.17.10.2843) and NVIDA NVS 5400M (version 9.18.13.4520).

Also Windows Media Player won't play mp4 files--just audio.

All of this worked on my machine not long ago.

I found relevant threads, but they don't seem to go beyond making sure you have the latest video drivers, which I did.

What gives?