2000 Chevy Cavalier Battery Problem

This morning my car barely started. Once it was started I put it in reverse and tried to apply the brake. The brake was oddly hard to push down, but it was enough to stop the car at the end of the driveway. I then tried to turn the car onto the street but the power steering wasn't working. At that point I knew that something was wrong with the car and proceeded to bring the car back up into the driveway but the gas pedal wouldn't work! Finally I looked over at the panel and saw the check battery light was on.

A few hours later I went back to check on the car; it worked perfectly! Any ideas on what is wrong with my car?

Note: The alternator and battery were replaced about a month ago.

Thanks,
Eric