No video in canvas monitor!!? Halp pls!

Hello!

A newbie here dropping in for some help from you esteemed video professionals.I've recently started using final cut after 10 years Avid use, for the most part an enjoyable experience. However I have a problem that threatens to ruin the whole experiment!

I was cutting a sequence last night and the video in the canvas monitor went black. Now I can't see any video in any sequence. If I match frame I can see the pictures, the seq filmstrip shows the frames and if I export a qt I can see the the entire edit?! Just no video in the canvas window? It's as if I've inadvertently turned off video monitoring?

I created a new project and imported some random clips and the problem persists, video in viewer and not in canvas. Can anyone help please?

I'll be your friend forever:)

Many thanks

Chris