Headunit resets all stations and memory from time to time?

Hey guys first thanks for the help.

I have a pioneer double din head unit that has worked flawlessly for 6 months. now all of a sudden

it resets from time to time, memory completely cleared and to default settings. no radio stations or eq or anything..

sometimes it does this every few days, sometimes every few weeks.

my power is solid to the battery, amp always powering on and no other troubles.

any ideas are greatly appreciated !!!