So I haven't played my ZT2 game in a long time like a REALLY long time...so long that it was before I upgraded to Windows 7. I decided today that I wanted to rekindle my long friendship with the game and start a new campaign but when I clicked on the desktop shortcut, it said something to the effect of "registry is missing". I took it as a sign that I should uninstall this then reinstall. So I uninstalled everything including the program files and the ZT2 folder and started from scratch. I installed the first disc which is just plain ZT2 and it was fine. I started with the 2nd disc, Marine Mania and it gave me the error code "16-something" and basically just couldn't install the expansion pack. I have several expansion packs: African Adventure and Endangered Species are the other two.
Any advice or help would be greatly appreciated. I know I saw on here where someone had the exact same issue but with all the computer jargin flying around I was really confused as to what I should do. Please explain in layman's terms. I'm good with electronics but I'm no expert!

Thanks!