iMovie11 upsidedown

Hi.

I have been using iMovie 11 on my iMac for a while (over a year) but now when I hover over a movie clip it shows as upside down. The movie exports okay and imports okay. I have tried resetting imovie by removing the com.apple.imovieapp.plist file. It is like the skimmer or video head has flipped it's previewer horizontally. Attached image and you can just see the red line with the clip upside down?? It is like i have hit some combination of keys.