It seems like this problem could be related to a corrupt AV or Firewall install or setting. Try the following:
0. Make a system restore point (
http://www.sevenforums.com/tutorials/697-system-restore-point-create.html).
1. Download (or find your hard copy of) your AV/Firewall software.
2. Disconnect your computer from the internet.
3. Boot into safe mode and uninstall your AV/Firewall software. (Some new AV/Firewall software can't uninstall in safe mode. If necessary, it's ok to do this in normal mode, but better in safe mode).
3a. Run the removal tool (last post):
http://supportforums.sunbeltsoftware.com/messageview.aspx?catid=23&threadid=5804. Restart the computer back into normal mode and attempt to install one of those programs.
5. Reboot, and then make another system restore point.
6. Now attempt to reinstall the AV/Firewall utility.
7. Reboot as necessary, and then attempt another install. Hopefully we are successful.
We create the restore points so that, if something bad happens, we can go back to where we were.
--Nick
