Well the trick is not to use the "User accounts" thingy in your control panel. Use your right mouse button on "My Computer" and choose "Manage". You will get a tree-structure display, where you can activate the admin account. Login under that one, delete all others and recreate them. Make sure you add them to the Local user group "Administrators". If you allready did this, then ignore it, but it could have to do with some profile settings that windows makes. If a virus was able to infect your System Restore points, it also can be able to rub off some of the windows default settings in any GUI/Wizard based Windows application.
Still i would vote for the full reinstall of your system, including a wipe of partitions and the MBR
"War. War never changes. Since the dawn of human kind, when our ancestors first discovered the killing power of rock and bone, blood has been spilled in the name of everything, from God to justice to simple, psychotic rage."
