Error 1935: An error occurred during the installation of assembly
If you are having problems installing any antivirus programs in your computer, I think your system has a problem. It is possible that there is a problem in the file system of your hard drive. An incomplete installation of a program can also cause this problem.
Abort your current installation if you are currently installing something and then check your computer for any possible errors. Any errors in the file system can cause applications to not work properly or any installations to go wrong. Use a disk utility application to check the system.
For a much thorough diagnostics on the system, use a disk utility application like Norton Utilities or Norton SystemWorks. Try installing again one of your antivirus programs after checking your hard drive.