Cs4 Insert Disk Why Am I Unable To Install Adobe CS3 After I Installed The CS4 Trial?

Why am I unable to install Adobe CS3 after I installed the CS4 trial? - cs4 insert disk

AMD Photoshop CS3 I Just Got The Creative Suite CS3. I had already installed the trial CS4 Dreavweaver. When the Creative Suite is installed on shared components and wrote CS4 then insert the disc. I'm on a MacBook Pro 10.4.11. I deleted all the "Dream Weaver" and even tried one of the cleaning program. No idea what could be causing this?