Mysterious "Server Execution Failed" Errors When Playing Video Files

Don't you just hate it when you either have a computer problem that's so unique, you can't find any mention of it in Google, or if you do find it, the "solutions" are so generic and vague they're all useless? I've been seeing the above error for months when using Windows Media Player 12 on Windows 7 to open and play video files. I've found other people complaining about the same problem, but the solutions presented don't apply to me (I don't run AV software on any of my computers). The basic problem is that: I'll double-click on a video file - and it can be any format, at any resolution - and Windows Media Player 12 will start to play the file. The file will play, and I'll click on the "X" to close the program. I'll double click on another video file, and every now and then, I'll stare at the spinning blue circle for 15 to 30 seconds, then I'll get the above error. It seems to happen on every computer I have, and I'm not sure if it's related to third party software - I don't tend to run stock Windows 7 for very long before I start to load my favourite applications. Any other Windows 7 users seeing this problem and know of a fix?