Simple as that. Playing an AVI encoded using M-JPEG produces black screen in all media players.
Disabling M-JPEG in FFDSHOW allows my other installed codecs to work... PICVideo M-JPEG 3 and MainConcept M-JPEG 3.2.4. Now all media players play the AVI just fine.
Thanks, I've been trying to figure this out for a year, why my MJPEGs only play with a black screen in Vista. I installed Pegasus PICVideo M-JPEG 3 and all is solved at last. Thank you!!