It is one of two things, there was an O365 version that struggled with the latest Intel Video Driver, so disabling Hardware Acceleration could help, another thing that it could be is an Outlook plugin, to test try using from the Run Box (Windows Key and type run) outlook.exe /safe
I got an update that fixed for O365...but I'm on Office Insider Fast....but I thought that update went out to everyone already. Are you using any Plugins?If it is the Intel driver does Microsoft know about the issue?