Failed removal of Trojan Horse

I'm running Norton Internet Security 5 for Mac on OS X version 10.9.4.

 

Norton found a trojan on my system a few days ago and was unable to remove it.  I wiped my entire system, re-installed all software (including Norton), and another trojan was identified this morning.  It's finding the trojan in a folder called "MobileBackups", but I can't find that folder anywhere on my system.  

 

Any ideas?  I really don't want to wipe my entire system again.  Not sure where this is coming from.