mediametadatahandler.dll - explorer crashes and restarts just for once or continually - in relation to video files (in a desktop or directory).

at worst: explorer continually crashes and restarts non-stop
(it seems caused by an mp4 file downloaded on the desktop - but strangely
it continues even when you move it in a directory)
at minimum: explorer crashes if you select an mp4 file from a directory (left/right clicking - there's no difference).

The details of the shell extension that might cause the problem:

Shell Extension Name:	Video Thumbnail Extractor
Filename:	mediametadatahandler.dll
Description:	Media Metadata Handler
Company:	Microsoft Corporation
Product Name:
File Version:	6.0.6002.18005 (lh_sp2rtm.090410-1830)
CLSID:	{c5a40261-cd64-4ccf-84cb-c394da41d590}

If you think that you have similar problem in your system, you can try to fix the problem by disabling the specified shell extension. In order to do that, simply follow the instructions below:

1. Download and run the ShellExView utility from this Web page.
2. Find the right shell extension according the details specified above.
3. Select this shell extension and press F7 to disable this extension. After disabling the shell extension, check if the problem still occurs. If the problem still occurs, you should enable back the shell extension by pressing F8, and then try to search for another shell extension that might cause your problem.

This shell extension problem was reported by HarryB