How do I prevent Adobe Reader from Launching

When I'm in the two pane mode (Lister View Pane) with a Viewer Pane on my right and I highlight, or should I say when I'm focused on a PDF file in the left pane whether in Detail mode, Thumbnail mode (displaying Thumbnails of the whole lot of PDFs in a folder, Adobe Acrobat Reader 8 launches and open the PDF under focus, instead of showing me a larger Thumbnail of the PDF on my Right Viewer Pane like I expect it to be or perhaps show me a larger than Thumbnail of the insides of the PDF on my right viewer pane.

Then each time because Adobe Reader 8 has launched with the focused PDF opened up in an Adobe Reader Window, I would have to close the window to return to DOpus. This is so inconvenient and driving me nuts.

This problem does not happen in the case of Powerpoints or JPGs for example, ie Powerpoint does not launch for example.

I have the both the PDF-ActiveX and PDF-Text enabled.

I find that the only way to stop the problem to get something shown "within" the Viewer pane is to disable the PDF-ActiveX in which case some of the PDFs display something (ie it does not display everything - just some picture, or words or some binary codes depending on which PDF is under focus, but at least the display is within the viewer pane itself.

Open Adobe Reader's Preferences and turn on Internet -> Display PDF in browser.

Thank you once again for the fast and precise response. Now I'm in PDF browsing heaven again.