Weird Quicktime .mp4 display issue

[trebblekicked]

mp4 files I encoded from flv to mp4 via iSquint which played fine for months upon months, now open up in the classic qt "audio" view (no video window present)

if i open the movie property windows, the video track is still there, and if i select the presentation>confirm aspect to: option and set it to classic, it plays fine.

any idea what's going on here? thanks in advance.

vitals:
QuickTime Pro Player v7.4.1 (14)
2.4Ghz iMac (most recent)