some question about user account

hi guys.
i am administrator in my system
1-if someone logg in as standard account or gues account and the system infected by a virus.does the system is stiil infected by the virus on administrator account?
2-i read the tutorial below:
Applications - Prevent Running Specified Programs
but it is only for .exe files .is there a way to prevent users from running specific file extensions like jpg or mp4 and etc...?
3-how to disable registry , task manager and command prompt in other users?

1.It's harder to get infected from a standard account than from an administrator account, as the later has more rights. But if as you said the virus can infect you from a standard account, your situation under administrator is worse.

2. As far as I know, you can only prevent applications that can run those jpg or mp4 files.

3. It seems you can do so in the group policy. Please do some google. It should be easy to find.

1-why it is harder?
2-you mean disable windows photoviewer and windows media player? but the user can install another software and watch them
3-i google it but i can not find anything good

Hi muiacir,

1. Because stand account has less rights than administrator account, that means it can do less damage when the virus has less rights. That's also why a guest account is the safest to use as it has the least rights among all account categories.

2. If you want to protect certain files from others to open, you should consider encryption software, such as Truecrypt etc, files encrypted are protected by normally a password.

3. Search "disable registry group policy" in google. I saw good results.