For Windows 7 64 bit users, the solution to this is the following:
1) Click "Start" -> "Run..."
2) type "regedit" and click OK3) locate the folder "HKEY_LOCAL_MACHINE/Software/Wow6432Node/VST"
4) double click the value "VSTPluginsPath"
5) clear the string complete
6) press enter
7) close regedit.exe by clicking on the [x] in the upper right corner
Now you can restart the installer and it should install.
The value "%VSTPLUGINS%" is not a valid path and is exactly the thing preventing the installation of the Virus Control.