Peugeot 207 faulty gearbox warning light

My 2007 Peugeot 207 1.6L automatic gearbox has 31,000 miles on the clock. Sometimes I get the error message on the display "info - gearbox fault" with a bleep sound, then it goes. Then I get the warning triangle light up, the snowflake symbol & sports mode "s" appear by the D symbol. These only go out if I switch the engine off. The car drives normally though. This usually happens when I'm driving it for the first time in the day. I have run a diagnostic tool on the car but it shows no errors but the error was not occurring at the time as I had switched off the engine.