Problem with widgets, can’t edit!

I installed widgets and “widgeted” my theme, but when I go to the Sidebar Arrangement and try to configure anything the hole wordpress screen gets dark and I can’t edit anything, trying to edit just get everything back, and the text area disapears.
Any suggestion?
It works with I.E. But I wanna use with firefox. Weren’t the wordpress guys that didn’t like I.E. at all?
Printscreen at I.E. > https://img160.imageshack.us/img160/8502/widgets5mr.jpg