can't export a quicktime in sbp4

Arggh, trying to make a quick time to show director . I went through the usual process and then a window appears telling me 'this is not a video file ’ . I don’t think I have done anything unusual or different to the way I export QTs .
I found that the file saves but with zero bytes. its only when I try to open it that the window appears telling me its not a video file ( which of course it is !!)
Help please . I need to export this today .

better contact support

After lengthy communication with Support they discovered that I seemed to have an arrant codec in my machine that was causing the problem . ( don’t know how it got there ) . But the guys solved it - thanks for the help.

Resolved by removing /Library/Application Support/3ivx/