If you’re trying to install Powershell 2.0 CTP3 on a Windows PC with Powershell 1.0 already installed, the installation wizard will stop with the following warning.
Before the wizard will continue, you have to uninstall Powershell 1.0.
Open Control Panel. Select Show updates and browse to Windows XP – Software Updates. Click on Remove to uninstall Powershell 1.0.
If you don’t have an entry in the Add/Remove Programs control panel, You can find the Powershell 1.0 Uninstaller here:
After uninstalling Powershell 1.0 you’re able to install Powershell 2.0 CTP3.