I recently downloaded the latest version of mplayer, and while I was setting it up I came across a strange problem with my windows configuration - it's lost the ability to open .avi files without first bringing up the "open with" dialog. I've checked what I believe to be all the relevant sections in the registry and fiddled about to no avail...I still can't get the damn file association sorted. When I select the "Always open with this program" checkbox in the open with dialog it has no effect.
Anyhow, I'm posting a screenshot of the context menu I get when I right click an avi file. Thanks in advance.
Go into your File Types list (Explorer --> Tools --> Folder Options (I don't have a Windows machine handy)) and then the File Types Tab.. Find .avi. This will list context menu options that are available, allow you to create new ones and let you select the default option.
I've fixed it now - more or less followed what HTRegz said. Basically the registry "stuff" associated with avi files got corrupted when I was trying to remove some "spyware" (a piece of software which forgot to uninstall a shell extension) and when I looked in the file types list it gave me the option to restore it to the default action.
As to what was happening when I double left clicked it - before I got rid of the crap associated with the shell extension it would attempt to run a non-existent program (which, btw had nothing to do with avi files :P), then after I removed it, when I double left clicked the "open with" dialog would come up (as in there was no open operation registered with it).