I'm getting a regular, once or twice a day, crash where the the Windows screen stops responding and panels and buttons flicker colour and transparency. I can't quit applications or navigate anything so have to do a hard reset. I have not changed my VM configuration, just upgraded Mac OS from Sierra to High Sierra and Parallels Desktop for Mac from v12 to v13. I'm using Sage payroll software and Office (Excel, Outlook etc) generally when this happens. Please can somebody help?