Welcome to forum SolidWorks Simon.
It's problem with graphic card. Try uninstal driver and instal new. If doesn't help you must send your cadr to service....
With all respect Lukasz, I don't believe it's likely a problem with the card. We've seen the exact same thing mulitple times over the years, on multiple SW certified systems. And we've only ever used nVidia cards. Like so many issues with SW, it's been frequent at times and then non-existant for long periods. This particular issue I haven't seen in quite a while and I'm certain we didn't do anything to "fix" it. Sorry I can't offer anything constructive to help you're situation Simon, although I agree that reinstalling the driver is good advice. We've been using SW for over 15 years and no matter the HW (again, always certified) or SW version, there has always been some graphic glitches. Some annoying, some maddening. Some you see once, and some reoccur for years. I see the same glitches running SW on on my MacBook Pro booted into Windows as I do on my new Lenovo and prior Dell Workstations.
Thank you both for the reply, I have updated and re-installed the driver with no effect.
My supplier (NT CadCam), has suggested turning on the Windows 7 Aero themes. (I have this turned off normally). Apparently SW uses this feature of windows 7. I have done this and will report back if it fixes the issues. 30mins of use tends to suggest it has, however, I'll give it a day or so of use before I report back if it's a success or not.
I am betting that the aero-on will be a good portion of the correct answer. This has been mentioned several times in this Forum. It seems counter-intuitive but does solve some problems.
By the way - welcome to the forum and feel welcome to both ask questions and give answers - we are all still learning!
I am running with Aero enabled and that may coincide with not seeing this in a while. At one point Aero produced intolerable flickering when switching windows for us, but since that has been fixed a while back, we've been using it.