Non-exempt salary status?

I am a non-exempt salaried employee. I do however get docked in pay if Im a couple hours late coming in or out for the day. The question I have is for this month (Oct 2008) Our paydays are 5th and 20th of every month. We have already been paid for this month. Time sheets are due the 15th and 30th of every month. The next pay period our 80 hours are already completed, so this entire week (Oct 27-31st) we are basically working for free. YET!! if I am late or absent this week, I get docked in pay from my paycheck on Nov. 5th. No one in HR at my POE can give me a staright answer. Can my company take away something their not paying me for?