Difficulty downloading pdf files, please read the additional details before replying?

I recently reinstalled my windows 2000 SP operating system and my adobe acrobat program. Previously I could click on my users manuals in my program files programs and also my internet pdf files and get an immediate page of clear English rather than the squares and other symbols that I get now.

I now have to open my pdf files through opening Adobe first and then using "open" in the File menu. On internet it's even more of a problem, I can't link my incoming emails to Adobe because although I've chosen "open Adobe on the internet", I lose this option when I select my emails.