Photoshop :: Text Edit Area Appears As Inactive / Text Box Invisible

I'm having this strange issue with the Photoshop type tool in Photoshop CS5. It might be, although I'm not sure, a bug. The tool itself is working and lets me add text and edit. But the box that shows up when editing text (and the blinking line that shows where I am in the text) - has gone invisible. I am having this issue in only one document. - I tested the type tool on other documents, and everything was normal. I've looked up shotcuts and hotkeys to check if I've tapped a key or something, but it doesn't appear to be so.
 
Now about the document; it does have quite the amount of text layers, and a lot of text in them. I've tried resetting the type tool, and I've restarted the program.
 
When I restart the program, the tool works as it's supposed to - but after editing or adding a new text layer, the editing area is gone again! Is this a bug, or have I touched keys that do odd things?