What is the cause of the problem and is it serious?

I have a late 1999 peugeot 206, V reg. model LX Automatic with 41,000 on the clock. Yesterday the 2 warning lights to the right of the gear map on the dashboard came on i.e. S and the one below that looks like a snowflake (page 128 of the handbook). The engine also seemed to have a different noise. I drove about a mile and then didn't use the car again for about 1.5 hours and everything was back to normal! The only mention of these bottons is on page 116 - instrument dials for automatic gearbox, where together they are described as 'operating programmes'

Any ideas would be welcome. I have no technical knowledge.

Thanks,