Clicking on anywhere on Admin Screen opens Thickbox

Hello All,

Probably the most strange and frustrating situation I’ve ever encountered, and I’m hoping one of you brilliant folks can shed some light on this:

I have a client who recently went in and updated to WordPress 3.7.1 without clearing it with me. Now when anyone logs into the admin area, clicking on any part of the admin screen results in a thickbox opening with the loading animation on a constant loop. Links, Check boxes, background, doesn’t matter, anytime the mouse is clicked anywhere on the screen, the thickbox loading bar comes up.

I went through and disabled all the plugins to no avail. I also switched to TwentyThirteen theme and still no luck.

Has anyone seen anything similar and perhaps found a solution?

Many thanks in advance!

Cheers.