Can’t edit text on one computer

I can’t edit text in the visual mode on one computer.

When I go in to type, I can start typing then I get a display of the word “loading” then it goes to white.

I can still type in the text/code tab but it won’t let me type in the visual tab.

The computer is an up-to-date MacBook Air. All software is updated. Flash is update. It won’t work on Safari, Chrome or Firefox.

Any thoughts would be greatly appreciated! Thank you so much in advance.

Bob