Snake, I have had similar problems. When you are doing the install, make sure that the CD is clean. Also, make sure that you have a complete disc (md5 check) and that you are only using 1 CDROM drive.
One other thing, if you get the 1 CD to install, you can do what fa0na0ki said, only use mandrake software update. It will ask you which discs you have, and you can tell it you have all 3.
Then go through and select which packages you want to install and VIOLA! there they are.
Did you buy the discs or d/l them? You may find out that you actually didn't want a lot of the stuff on the other 2 discs anyway. If you are looking for a specific program/game you can always just plop in the CD and go into the RPM directory and install it.
I love Mandy 8.2 so if you have any q's, please don't hesitate to ask, I would love to help.