This maybe a property sheet handler that's attempting to read the file's contents, essentially stealing it away from uTorrent. Start -> Run -> "regedit" Open the hkey_classes_root and find the .AVI folder, click on it. If it has a subfolder called ShellEx with some other folder {xxxxxxxx-xxxx-xxxx-... } inside it, rename ShellEx to _ShellEx or something else so it doesn't find it. Note the value of the {default} entry and scroll down in the left pane, past all the extensions, until you find a folder named that entry (probably avifile or something like that). Open it, and again rename any ShellEx to _ShellEx. This should disable all context menu and property sheet handlers for the .AVI file type. See if that works.