Nokia N 73 Music Edition
Memory erro

I m suffer from memory error in my nokia cell phone... i also format my mobile from nokia care... to remove this error... the error is temprerly out... but some time they atteck again on my mobile... they shows a msg "MEMORY FULL DELEATE SUM DATA FIRST"... and i have 600mb free space.why they show low space??..so plz guide me.and tell me.how can i remove this memory error???..