I have lost partial User Admin Rights for all users who earlier had admin rights in my laptop with XP Pro and in my PC with XP Home edition. Both are standalone computers and are not part of any domain. I already tried different things in the computers to rectify the prob, including going through the other solutions in Techrepublic, but nothing is helping me out. The user rights are showing administrator correctly in control panel, though I am not able to install Service Pack 3 (XP Pro) and some other applications… getting error that I donot have sufficient admin rights to perform the task. However some applications and updates are getting installed fine without any problem. But most of the big applications are not getting installed. Also I am getting errors that I donot have sufficient privilege to make the change, whenever I am changing any settings in MSCONFIG, though the changes are going through fine but with the error msg. Please help as I cannot install lot of important security updates including Service Pack 3 and also some other imp apps. Thank you in advance for your support.