The colorful theme aligns with the visuals of our modern Office apps by bringing their primary accent color to the ribbon.
When you first start up any of the latest Office apps you’ll be hard pressed to actually find what’s new.
Then you can try to open Excel in safe mode, but your problem is random.
You can just try it, if it works fine you can try to disable add-ins in Excel.
Microsoft has not provided any offline installer or standalone ISO files of Office 2016 Preview.
The company has just released a small online installer which is also known as Click-To-Run (C2R) installer to install the free preview in all computers.