MinosTheNinth - 9:33 am on Aug 28, 2012 (gmt 0)
I am sorry for very quick reply, but now I'm a bit in hurry. Anyway hope, this will help you.
With rule ^alice\.html$ bob.html you say, that everything that only exact "alice.html" is rewriten.
The ^ character marks start of tested URI and $ marks end.
Try exclude ^ character from rule and it should work as you expected.