How is her behaviour while she is at daycare?
If she is having behavioural problems there, what are the consequences for her?
Personally, I would be very reluctant to take a 2 year old to a psychiatrist.
After working with preschool children in preschool, daycare etc for 20 years, I can tell you , there are some very stubborn kids out there.
The key is firm and consistant disipline for unacceptable behaviour. And yes, supernanny is great!!!
Good luck, remember, theres always challenging times with children, and 2 years olds are challenging!!!!