Apparently, she had a system sorted with her family so that she would know if she was getting bad press, her family would let BB know that her "sister was ill", and BB would have to tell Dawn. This was in fact not true and the "code" for bad press, which is why i suppose she wanted to leave. BB apparently figured this out and therefore ejected her for breaking the rules, before she could walk. This may again not be true, and BB may have made this up so it didn't look bad with 2 walk outs before the first week had ended.
See
here for all the details.