radio not functioning right 10 minutes then works fine ,when you turn off car sa on 2011 Nissan Sentra

when car is turned off radio cannot be controled for about ,10 minutes then works finewhen car is turned off same thing again with radio

Asked by for the 2011 Nissan Sentra
When it comes back on, are all the preset (favorte stations) memory lost? Clock, if equiped, show the wrong time? Any warranty left?