Arial Font Problem

My system font Arial keeps getting replaced with a font called Jungle. I clear the cache, restart my computer and all is good for about a minute then it starts all over again. I checked Font Book under "All Fonts" and where "Arial" should be in alphabetical order is that font called "Jungle" I click on it and try to delete etc., but when I restart and open up TextEdit or Safari, that font called "Jungle" I just deleted comes back replaces "Arial" again...this is driving me nuts! I can't keep clearing the cache every 5 minutes. Can somebody help me?