Blocking Websites Without Using Host File?

I'm currently working on a program which will block the users computer from viewing websites that contain Malware, Spyware, etc. on them. I do have a VBScript code that does overwrite the windows host file but once executed my Microsoft Security Essentials says that some program or virus is trying to alter windows host file or something around those lines.

My question is, is there any other way I can block these other websites without having this problem occur? :confused: