My E4402B give the message "unable to load file" when I try to load a limit. If I try to create a new limit, it will only allow me to enter two points and when I try to save the limits file, I get the "white screen of death" and the unit reboots. When it comes back up and I go to "system" "show errors" it says -310, System error. I thought the firmware might be corrupt so I downloaded the lastest version and installed it but no joy. Does anyone have a suggestion (other than an extended vacation in California)?