Yesterday I updated my Acrobat Reader from 5.x to 6.0, and removed the old version. Now neither Netscape (7.2) nor IE (6.0) are capable of opening pdf files (Acrobat Reader works well standalone).
I cannot find anything in Netscape pointing to the old location of Acrobat Reader so that I can change it. I did add in the Preferences/Helper Applications a line telling it to open application/pdf files with the new reader, but that has done me no good.
The Netscape and Adobe sites seemed uninformative.
My usual browser is Netscape, but I would also like to fix IE, though that is a much lower priority.