Within the next few weeks I hope to have the last part of the brake job done on my car- the frt. pads and rotors. However, there's another fairly recent problem I wanted to bring up- when braking, either lightly or hard to set up a turn, my pedal gets rock-hard (very difficult to push down) and the brakes feel like they're not working right (ie not grabbing like they ought to). I get a little nervous when this happens in traffic, as stopping distance increases; I'm thinking perhaps the brakes simply need a good bleed job. Cold it be air in the lines? Is the vacuum power booster going out on me? Help! (before I ass-end someone else

) I check the master cylinder regularly, I know it's full, so I logically ruled that out. What the heck is going on here?