Problem 'Failed symlinking runtime library. Falling back to copy.'

I'm having this error a couple of times on every build. I've tried disabling all postprocess scripts but this keeps occurring, so I guess that it's something internal.

 Failed symlinking runtime library. Falling back to copy.
 UnityEngine.Debug:LogWarning(Object)
 PostProcessiPhonePlayer:SymlinkFile(String, String)
 PostProcessiPhonePlayer:InstalliPhonePluginFiles(String, String, String)
 PostProcessiPhonePlayer:UpdateInstallLocation(String, String, String, String, BuildOptions, Boolean, String)
 PostProcessiPhonePlayer:PostProcess(BuildTarget, String, String, String, String, String, String, String, BuildOptions, RuntimeClassRegistry)
 UnityEditor.HostView:OnGUI()

Anyone has an idea?