Premiere Pro 2.0 Installation Problem

Hi,
I have been using PPRo 1.5. Yesterday I bought the PPro2 as PPro 1.5 is giving me a lot of trouble during encoding. So untill that issue is resolved I decided to use PPro 2 and see if that solves the problem of PPro 1.5. Before installation I uninstalled Ppro 1.5, deleted all the related folders and then tried to install PPRo 2. But everytime, after language selection it gives a massege that

"A previous version of this program is already installed......setup can not continue....remove the previous version using Add/Remove program."

I did all these before installing PPro1.5. I tried to clen the registry using Registry First Aid, cleaned Temp Folder,Rebooted but still I'm getting same error massege.

One information : at the time of its first release I had PPro2 tryout installed in my computer.

Could some one please help me?

Thank you.