Ok, then find the problem key at the registry (in this case, it is the DA42BC89BF25F5BD0AF18C3B9B1A1EE8) under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData \S-1-5-18\Components Now, follow the nightmarebr post (1st page) on how to change the permissions for that key,then delete all the values, except the (Default) Now install the cs5.