A WebmasterWorld thread informs that Microsoft interface is not allowing a bid for less than $1. If in Microsoft AdCenter, you try entering a bid for less than $1, the interface would automatically push it up to $1.00.
"Anyone seeing new keywords submitted not allowing the bid amount you want to be accepted? i.e. if you are trying to submit a new keyword with a bid for, say, $0.15, the UI keeps returning $1.00 or some other higher amount. Seeing this across many, but perhaps just 5% or so, of new keywords I am trying to submit."
Microsoft AdCenter representatives confirmed the issue and said would fix it up soon.