Hello Jeff,
Have you tried creating a new Administrative account while under your son's account? Try that first. If that doesn't work, try elevating your son's account type from user to administrative. Does that help you out?
As far as deleting the virus, there is a very long download that creates a live CD called BootMedic. You download the 32 Bit version from here:
http://download.cnet.com/BootMed/3000-2094_4-75448200.html; and the 64 Bit version from here
http://download.cnet.com/BootMed-64Bit/3000-2094_4-75450831.html.
Once its been downloaded, right click on the file to unzip it, then right-click again to burn the image to a CD. From there insert and reboot your PC. Among other applications is an antivirus application that should let you get control of your PC again.
If you have any questions or need further assistance, post back here and I'll assist you.
Let me know if this helps you out.
Regards,
BearPup