PDF file confused?

I have several PDF files in a group. When I double click that group it opens in a separate window. When I double click on any of the PDFs it opens that PDF in a separate window.

Except one. For that PDF, when I double click on it in the group window, it simply takes me back to the main DevonThink window with that PDF selected. (From there I can open the PDF fine).

Any idea why?

For that same PDF file, when I try to open it with Skim it hangs Skim at 100% CPU. I suspect these two are related.

I noticed these problems today. Yesterday all seemed fine.


The reason for this is probably that DEVONthink usually reuses windows already showing a document instead of opening a new one.