Windows Live Movie Maker is one of those under developed application that don't handle variance very well.
The exclamation marks; they can mean basically one of a couple of things when you are dealing with Windows Live Movie Maker. They can mean the video you are attempting to work with isn't supported [or is, or has become corrupt], or you are out of system resources, etc. And there are suggestions for all those issues.
A lot of the time, it's codecs…
CODECS; What you need to know about codecs, in a nutshell, is that they dictate whether or not the audio, video or both are recognized properly by Windows Live Movie Maker, and it's important to have the right codecs installed/updated. It affects the performance of Windows Live Movie Maker and it also affects the rendering of the videos/audio inside the application— And Windows Live Movie Maker offers no automated assistance in resolving the issues of codecs. And if you're under the illusion that just because Windows Media Player can play the file, it should be good? That'd be wrong. Loading codecs for Windows Live Movie Maker is left to the users/customers to find and install...
Codecs Not installed/Format Not supported
Windows Live Movie Maker supports many formats; but what's not provided to the public [regular users] is that Windows Live Movie Maker doesn't recognize those various formats unless the CODEC for that format is installed in the operating system; it's not built-in to Windows Live Movie Maker. And Windows Live Movie Maker doesn't make any attempts to identify or get those codecs for you.
If you're having any issues with audio/video media, one of the first things you need to do is find the right codec to use; and you need a program that can do that for you.
I wrote a post on how to find the codec that's being used and how to find the codec for you and Windows Live Movie Maker.
Windows Live Movie Maker isn't compatible with a lot of the formats it says it's until you load the CODECS in to the operating system. If you're having issues/problems with opening/editing your audio/video media, it could be your installed codecs [or the lack of] or maybe you need to update your CODECS; ultimately, it's all about the CODECS.
Audio and Video, both, require current CODECS to play the proper media [correctly].
As a suggestion, you can download the most ubiquitous CODECS yourself and installing them very easily...It's FREE, REPUTABLE and updated regularly.
Windows Live Movie Maker resources…
The more you add to Windows Live Movie Maker the more memory the application uses; even more so when you have a large video you're putting efforts in to create. Windows Live Movie Maker can easily consume 1.5Gb of memory for creating a video. This can be proven just by loading a large video and then scrolling down in the story board; Windows Live Movie Maker puts EVERYTHING in memory.
This affects it's ability to read, recognize, render, save and export to YouTube and Facebook; everything. It's already been confirmed in this forum that depending on what you're working on, and how big your video is, you may not be able to save your project or export [render] it for a WMV, DVD, YouTube or Facebook.
Windows Live Movie Maker is really bad about handling system resources and can cause plenty of issues. To check on this, if you run in to issues with Windows Live Movie Maker, pull up the Task Manager and see how much Windows Live Movie Maker [the application] is taking/using from your system. If it's using more memory than anything else, that could be your problem…
To cover for the consistent reports of resource issues in Windows Live Movie Maker; the standard response from Microsoft techs is to adjust your PAGEFILE — it's helpful in some cases.
As a recommendation— In the Initial Size box, enter a value equal to one and a half times the amount
of the computer's installed RAM. In the Maximum Size box, enter a value equal to twice the amount of
the Initial Size value.
Note: You can change it back to what it was if this doesn't work for you…
Video has become corrupt
There's always a chance that the video you are attempting to load is corrupt; yes; there's a chance— and there may be no way of fixing that. There's a few program scattered on the Internet that can make an attempt to repair the video file…
But in the case that you are working with perfectly good video and then suddenly the video stops working or goes black— I would have to say resources are the culprit. Rebooting may be your only resolution there.
If I find anything else, I'll update this post.
Windows Live Movie Maker support forum:
If you'd like, you can leave feedback for the Windows Live Movie Maker 2011 team for suggestions/improvements:
I hope this helps...
Larry Henry Jr.