What would cause controller to reset back to defaults?

I have a printrbot Simple up and running with the Marlin firmware. I'm getting good prints and everything's nicely tuned. Yet today I noticed stuff was really out of whack. After looking and double checking everything I finally started looking at the eprom settings, and that's when I found that all of my previous entries were gone and it looked like it'd been reflashed back to factory settings. Everything was previously written to the eprom as I've been printing solid for the last week.

I routinely disconnect and power down at end of day. So what would cause it to act like it'd been reflashed? Fortunately I had all of my settings jotted down and prints are back to looking normal, but now I guess lesson learned is to just double check the eprom settings as I was tightening the lines and adjusting z height when the problem was elsewhere.

Unless there is a convention that a blank eeprom reads as defaults, there's no way to get it back to defaults without reloading everything. I would suggest using the flash for you defaults and turning the eeprom off.

Can anyone expand on how the eeprom works? and/or where in the firmware the default settings are that will be loaded into eeprom when reset to defaults? I currently have eeprom disabled cause when I was calibrating my printer, I would make the e-steps change in the firmware and reflash. Worked great and then I decided to try enabling eeprom so I could make "on the fly" changes while printing but when I pull up the values,on the lcd display, assigned in the firmware they do not match the values I've changed in Configuration.h? It looks to be storing default values in eeprom written somewhere other than Configuration.h?
I would like to have eeprom enabled for real time changes but would also like the initial values it loads on default to be the ones I've calculated during calibration and changed in Configuration.h.....anyone know how to accomplish this?