How can I fix my Citroen C5 02 2L pet wagon?

Two issues actually which someone may be able to help with.. 1st, occasionally whilst driving along, the driver's side electric window will operate down of it's own accord!! I'll click it back to closed and then a kilometre or so down the road it will do it again!! On one 200km journey last week it happened 6 times in a row but only during a 10km stretch of driving! Weird.. has that happened to anyone else? It happened once again only a couple of days ago (window went down only once this time) but's been ok since????
The second is the Antipollution fault warning light coming on (& engine/service light) when the car runs beautifully?... appears to be a common complaint with not too many answers! Any advice or similar experiences would be appreciated. Thanks Paul H