H4 visa interview: doctor; visitors visa was rejected recently

[sandman28]

My wife is planning to appear for her H4 interview this month. She is a doctor, has given 2 of her USMLE exams. Her visitors visa was rejected in Feb. She was still single then. Reason for refusal: potential immigrant

I'm an engineer on H1. Documents are all in good standing. My visa is valid till 12/2011. I'm pretty concerned about her chances.

What kind of questions could be expected? Any discussion/suggestion/advice is much appreciated

thanks