Uninstall Adobe Reader. You don't need it.
Otherwise open:
My Computer --> Tools --> Folder options --> File types
PDFs will be listed as Adobe Acrobat Document
It's helpful if in the Registered file types: if you click on the gray bar where it says File Types so you can get them in alphabetical order.
In your case, it would seem that the Adobe Acrobat Document must be associated with Adobe Reader. Once you highlight the Adobe Acrobat Document, you will see Details for "PDF" extension and under that it will says "Opens with" There is should definitely tell you what it opens with. Either your Reader or Adobe Acrobat. If it's with reader, then click on change and change it. If you don't see the Adobe Acrobat listed then browse to it. It should be in this directory: C:\Program Files\Adobe\Acrobat 8.0\Acrobat
hth
