My wife entered USA in May'08 on H4b visa. She got H1b approval as of October'08 and her employer filed COS which got approved end of Dec'08. She has been on bench ever since and only have two pay stubs(Out of status).We are planning a trip to India and I want her to change back to H4b.

My questions are
1)As she has a valid H4b visa stamped on her passport which is valid till Jan 2011, can she leave USA and come back on the same valid H4b visa,as I still have a valid H1b visa in status, without re-applying for H4b or COS application in USA?
2)If she comes back on H4b visa, will there be any complication at the port of entry as she didnot file for COS back to H4b in USA and didn't re-apply for H4b visa in India?