Can no longer preview files while downloading

[theladofsmiles]

Sorry if this has been asked before. I've just upgraded from 4.26 to 4.81. I used to be able to preview files just by double-left-clicking them in the Downloads pane and Windows Media Player or WMP would automatically launch and play them. Now, double-left-clicking doesn't work, and neither does selecting them first and then clicking Launch.

The funny thing is, if I use Windows Explorer to go to the Incomplete folder, I can double-left-click on any file (except AVI - see below) and they will launch and play automatically in WMP, so I don't think it's a problem with my file associations. How can I fix this, so it goes back to how it was before? There doesn't seem to be any options in LW to fix this.

Now, related to this, I've been tearing my hair out about corrupted AVI movie files. I want to be able to preview a AVI file, instead of waiting for the 700Mb file to download completely, only to find the mutha won't play, no matter what codecs I download. There are LOTS of posts about this issue, and the solution to avoiding those planted corrupted files is preview first. What can I use if WMP won't preview?

Oh, what exactly is an AVI file, anyway - does it include DivX and MEPG4 formats? Why can't I even use WMP to preview a half-complete AVI, like I can with a half-finished MP3 or MPEG? I'm hoping someone can at least recommend a fairly simple one-stop-shop solution for previewing files externally if the double-left-clicking-within-LW problem can't be fixed. Thanks!