Insert/Edit Link button Gray. Can’t Add Links

I’ve searched the whole Internet, but can’t find the solution. Well it feels like it.

I can’t add a link to a post. As the title says, the buttons in the Visual editor are gray. If I manually add the link code in the HTML editor, the text appears in the post, not the link. I can add a STRONG tag, so HTML is being parsed. I also deleted and copied the freshly downloaded wp-admin and wp-includes directories and contents. I can get the Insert/Edit Link dialog box if I press Shift-Alt-A, but after I enter the fields pressing the Insert button only clears the info I just put in.

I tried changing the editor to TinyMCE, but I got a “wrong datatype for second argument” error, so I deactivated it.

I’m only using the Akismet plugin, but I tried turning it off with no change. I’m using the Default theme.

Thanks for any help.