In Explorer, go to Tools/Folder Options/File Types. Scroll down until you see the PDF extension. Highlight and delete this type of file. Next, find a PDF document and click on it. You should be presented with a list of programs to use to open the file. Find Adobe Acrobat and click on that. This should reassociate Adobe with PDF files. Good luck.
I am using Windows XP and Adobe 6.0; the document I am attempting to open shows up as an adobe document , but when attempting to open it my system default to MS Word and I am not provided with the option of specifying what program to use .