What explorer will be doing is calling into a shell extension to generate the video thumbnails. Under some circumstances it ends up blocked on the shell extension.<p><a href="http:&#x2F;&#x2F;blogs.technet.com&#x2F;b&#x2F;markrussinovich&#x2F;archive&#x2F;2005&#x2F;08&#x2F;28&#x2F;the-case-of-the-intermittent-and-annoying-explorer-hangs.aspx" rel="nofollow">http:&#x2F;&#x2F;blogs.technet.com&#x2F;b&#x2F;markrussinovich&#x2F;archive&#x2F;2005&#x2F;08&#x2F;2...</a> (not precisely the same thing, but related)<p>I&#x27;ve personally seen opening a folder full of photos produce a crash dialog pointing the blame at an Nvidia DLL.