LaTeX.org

Reboot your system without the second monitor attached to it - that should definitely do it.

Did you change your Acrobat Reader?

I once had a problem similar to that - it turned out that the new Acrobat Reader didn't like one of the options I sent to close the document. However, I cannot remember what it was exactly.

Still, consider that it might not be the TeXnicCenter...

In the subfolder of your TeXnicCenter installation \packages you will find a file "Tex.xml" it holds the auto-completion data that TeXnicCenter uses.

If you look through it, you will probably find that the template there is wrong. If you look at the file closely, you will figure out how to change ...

It's definitely the update of JabRef! I had the same problem...

Switching back on JabRef is a pain though as the new JabRef-Version uses a new file format that's not backwards compatible ('"file" changed to "pdf", etc.)

However, I found a rather strange workaround:

Start TeXnicCenter first ...

It might be this one:
http://www.latex-community.org/viewtopic.php?f=31&t=371
Try it...