Hi guys! First time here, and boy do I have a problem this end. I am trying to mix a cleaned clip of music with some video I created, having split the old track off my video and deleted it. Now, when I add the new audio on and go to play the clips back in the preview, the video looks like a monet painting which has been horizontally dismembered.
Imagine static on your tv, but think of a very poor television signal with all the image broken and out of sync, and you get the idea. I can hear the audio absolutely fine, but the video is 100% unrecognisable.
Any thoughts as to what may have caused this please? I am up to my neck in video codecs, and audio codecs, since I do a lot of this kind of stuff as a sound engineer - but this has utterly got me stumped.
Just for the record, this is the format base for what I'm trying to mix (just in case there is any incompatibility anywhere...):
Base video: H.264 - MPEG-4 AVC (part 10) (avc1) 480x360 Planar YUV 4:2:0 30 fps
Base audio: MPEG AAC Audio (mp4a) Stereo 32bit, 44100 Hz sample rate
Thanks for any help you might be able to give in advance 
Ed G.