First you have to be logged out of the site. I don't know if you can actually do that with the priority login you have through the backend.
I click on COURSES in the menu on the left.
There being only one course, I click on the details button and then on the next page the Enroll Now button and the screen goes blurry in Firefox. In Chrome it goes blurry with the signup box also blurry. It could be filled in in Chrome, in you could read the text.
Here is a screen capture of the 2 browsers.
WHile deleting plugins and there were only 2, I did try to delete the WPMU Dev dashboard. That created a problem for me accessing the backend at all. Does the dashboard need to be installed to install the plugins, and why can't you delete it, if bandwidth is an issue?