Absolutely could be. When was the last time you updated your graphics card driver?
Did this just start happening or has this issue been going on for a while and with other models.
Do you have the latest service pack loaded for your version?
When 2014 arrived, the certified driver also had to be updated on my machine.
I would suggest running SolidWorks RX and allowing it to check your system. If the graphics card is not up-to-date it will give you a link to the latest suggested driver.
Thank you all for your feed back. my driver was from 2011 it helped with the update - somehow I had also forgot about the RX - helpful.
Thank you and have a nice weekend! - it is late afternoon here in Denmark