I have Windows HP with Vista Sp1 installed on my Black Viper tweaked pc and am very satisfied with its performance ; however I wish to install Win Vista SP2 and have run into major roadblocks . I have read through many suggestions on this topic but still no joy after a month or more of trying . Initially , the download would start , then stop after 99% was installed and revert back . Now when trying to install , I get a message that SP1 is not installed and I must install it first . SP1 is installed but I tried to reinstall it to no avail . When trying to reinstall SP1 I get a message that SP1 is already installed , then the reinstallation stops . !! Yet , my attempts to install SP2 tell me I must first install SP1 . I have tried the SFC / SCANNOW and chkdsk /r repairs to no avail . I have also tried repairing my system with the Microsoft OEM HP installation disk but the repair does not address my issues . I do not wish to reinstall Vista from scratch since my system is working very nicely except for this glitch . I am chasing my tail and need some help with this problem . Thank you .