photoshop

Do you get any error message while installing it? Are you installing it from the dvd directly or using the downloaded file?

If installing from dvd directly, i'll prefer to install it from the desktop and check. http://helpx.adobe.com/creative-suite/kb/install-creative-suite-5-cs5.html

Also, try the below suggestions :

Turn off User Account Control : http://helpx.adobe.com/x-productkb/global/disable-user-account-control-uac.html

Restart Windows in a modified mode | Windows 7, Vista - http://helpx.adobe.com/x-productkb/global/restart-windows-modified-mode-windows.html

Create local administrator account | Windows 7, Vista -http://helpx.adobe.com/x-productkb/global/create-local-administrator-account-windows.html

Attach the error screenshot, incase of same error.