White Canvas Screen in FCP 7 Studio ???

Ive just had to re-load my copy of FCP7 Studio due to a drive failure. It seems to be working fine except for an oddity that I can't figure out the what or why on.

The Canvas screen is all white, except when the timeline is actually playing. If I stop the playback to make an edit or adjustment the Canvas goes completely white, select a clip of the timeline and hit play, it plays fine in the Canvas window.

I've obviously changed a setting somehow / somewhere but cannot figure out what that could be. Can anyone help please?10.8.5

The Mac's OS is 10.8.5 Mountain Lion.

Thanks!

PM