Widget drop-down/drag and post "add media" button don't work

As the topic says, no widget drop-downs will work, or even appear. Anything that is draggable for whatever particular theme I’m using gets the crosshair arrow thing, but doesn’t drag. When I press “add media” in a post, the screen moves a bit but no menu comes up.

I have tried disabling all plugins, and the problem still persists. I have also tried using the default 2011 theme or whatever, but no buttons will drop down in that either.

I’m really pulling my hair out over this; haven’t been able to post for a while and I’m tired of all these weird problems.

A side note is that I updated to the latest version, but this was after I already had this problem and did all the steps I mentioned above. I was hoping maybe updating everything might do something, but no dice. Prior to, I had been using version 3.3.2 for a good while.

Any suggestions?