Yep, settings, patches etc. are stored battery powered SRAM and when it dies, the amps do strange things.
It's soldered into the main board so you have to be handy to replace it.
They are supposed to last six years or so depending on stuff.
It takes a 3 volt lithium CR 2430 cell that you should be able to find at a hardware store. The manual says if it measures any less than 2.7 volts you should replace it. Be sure to measure it place, not just open circuit. Although there isn't much current drain from it in use, only about 3.7 microamps or so according to the book.