sounds like maybe you have a corrupted install. try disk utility and repair your disk and permissions if that does not help make a second partition and install a fresh copy of osx to it then see if it persists if it does redownload your os and remake. i just had a similar issue with a real mac and app store. every time i tried to download mavericks storagent would consume all cpu. it shows in activity monitor. right now I'm re re installing maverick but from the recovery partition it creates on a mac.