Is there a way to not get virus for roblox

There are no viruses on Roblox. Roblox.com does use cookies to help identify your computer. These are not harmful however and are not viruses.
Unless, you ment by in-game viruses. They usually only cause lag.
http://wiki.answers.com/Q/How_do_you_get_rid_of_the_'Infected'_script_on_Roblox