Blank page edit window

Hi — When I go to edit any of my pages, the visual edit window is blank. When I click on text, the window collapses. I reinstalled the latest version of WP, I updated and deactivated all the widgets. I tried using a different browser and deleted the cache (this is the one thing I am not sure if I did successfully in Firefox, but I did do it in chrome.) Still no luck… basically I can’t edit anything, so any advice would be very much appreciated!