[MacDV] Using QT Pro 7.6.3 to compress video clips for Mail

[TUCKER ian]

I recently was advised by list members to go to "Utilities" and use QT  
7.6.3 to continue compressing QT movies for transmission by "Mail".    
This worked for awhile, but now,  just before completing the export to  
Mail,   I am getting the following message:-

Share "XXXX" to Mail

Failed : qtKitErrorCatchAll(-50).

I have tried re-installing QT, trashed plist files etc., but to no  
avail.

Any clues please?

Thanks,
Ian Tucker