.mov movies not generating thumbs

Not sure what happened. Everything's been working great, but suddenly there are no thumbs being created when I upload .mov movies. Flash movies work fine, and I haven't tried other formats in the past couple days. Is this a mencoder problem? I'm not sure how the thumbs are generated exactly.
I looked in the debug.txt file, and everything seems to be working fine.
Here's a snippet from the debug.txt for the last .mov movie I uploaded:

2007-12-14 11:00:11 Video id: 160
2007-12-14 11:00:11 Calling ffmpeg-php -> ffmpeg_movie()
2007-12-14 11:00:11 Get video duration - START
2007-12-14 11:00:11 Get video duration - END
2007-12-14 11:00:11 DURATION: 144.853333
2007-12-14 11:00:11 Create Thumbnail - START
2007-12-14 11:00:27 Create Thumbnail - END
2007-12-14 11:00:27 CONVERT COMMAND:

It seems like the thumbnail command is being executed, but the thumbnail never ends up in my thumbs folder.

Any ideas?

in vshare 2.5 thumbs are created using ffmpeg, in 2.6 you have a choice of taking them with ffmpeg or mplayer/mencoder. i know mplayer/mencoder supports formats ffmpeg doesn't so that should be able to take the thumbs on the videos codecs ffmpeg doesn't support.

Thanks Leki,
I'm still using 2.4, but I guess that's a good motivation to upgrade to 2.6 when it's released.
So I guess my problem is with ffmpeg...that's so strange that it works for some video formats but not for others.

Can you provide url of the video (.mov) having thumbnal problem or try upload it to http://video.bizhat.com ?

Thanks Admin,
Once again, you're on top of your game. I just tried uploading the video to Bizhat (http://video.bizhat.com/view/1326/snow-angels-trailer/), and there again was no thumb generated. So I guess it's a problem with the video and not with my site. That's still strange though...both videos were from Yahoo Movies, so maybe there's something in their encoding that screws with the thumb generation.

its just that mencoder supports more codecs than ffmpeg.......i think about 30% of videos on my site have broken thumbnails....cant wait for 2.6 so i can fix them all with mplayer.