channel strip & image construction errors

Hi you lovely people,

I’ve got a problem with some sessions I recorded recently. After a while I will get image construction errors on all the tracks and have to roll back to a back up - which will then more often than not fail in the end too. If I’m particularly unlucky I will also get harsh sound problems from the audio.

I’ve also noticed that the in-built channel strip also has some issues when it’s all going pear-shaped. If I click on the compressor for example none of the controls show up.

I’ve got a feeling it’s something graphics related but have no idea what to do to fix things.

Cubase 7 (latest update doesn’t help)
Macbook Pro late 2011. 16gb RAM.