Nero 7.0.8.2 won't start

I’ve just purchased the upgrade from Nero 6 -> 7, but I now find Nero and Express 7.0.8.2 won’t start - it just sits in the task manager using 0% processor. All the other apps work fine, and I’ve tested previous versions before. Tried reinstalling and the nero clean tools, but I’m guessing something might be interfering with it?