Fed Policies

Following up on my post earlier today, why would a commercial bank lend in the federal funds market at 0.25% when they can get 1% on their reserves at the Fed? Will paying 1% on reserves deposited at the Fed have the effect of setting an interest-rate floor on lendable funds? And, if so, won't that policy create a serious liquidity problem no matter how much liquidity the Fed tries to create?

Update: I see (from here, for example) that the Fed has lowered the interest rate it will pay on reserves also to 0.25%.