You have some other Adobe software on the system that has stored persistent path information e.g. for a shared component that originated from another source. You will have to run the Creative Suite Cleaner Tool and try again. also, when using disks make sure the original folder structure matches the real thing, i.e. the setup.exe is at the root level. Nested folders can also cause all sorts of weird issues when they point to a wrong install source file...
Mylenium