artist 6.5 to artist 8

I just upgraded from artist 6.5 to 8. After installation, when I click on the artist8 shortcut I get an error message saying… 'DWM COMPOSTITION IS NOT RUNNING. PLEASE SWITCH TO AN AERO THEME."

I have no idea what this means or how to switch.
Can someone please help me. In layman terms.

Hi and welcome in Cubase Artist 8,

Please, read this Knowledge Base article, which is exactly about this error.

That was the problem! Thank you for your knowledgible reply.