Can't add graphics etc. to pages/posts with "Add Media" button

Hi:
Client site uses C-Star Design theme. It is up to date, and has been for awhile. Went in the other day to update a page and saw that some plugins needed updating. Did those and the “add media” function stopped working. If I go to a page (site is not using a blog) and click “add media” the normal windows come up, and I’m able to bring a graphic or pdf into the media library, but cannot then place it in a page. I can’t place an image that I bring in from my computer either. If I manually enter the link of the item, if it is in the media library, it will appear on the page. But the “insert into post” function does nothing.

I tried deactivating all the plugins and tried to add an image. Nothing. Left the plugins deactivated and switched over to Twenty Eleven, and can use “add media” as normal. Reactivated C-Star – won’t work again.

Since the theme is up-to-date, and hasn’t changed for awhile, why would it now not work? Can anyone suggest anything?