this method to manually tell Windows to use Adobe 6.0 for pdf files by default.

1. Select/click on the pdf file
2. File -> Open with -> Choose program
3. Select Adobe 6.0 if it shows up as a list

From this point on, windows should remember Adobe 6.0 as the pgm to run when you double-click on any pdf files.

If you still have any problems, I would un-install Adobe completely and re-install the new version again. The install should define the correct Adobe pgm to execute when you open a pdf file automatically.