Car grinding when starting..? HELP!

I have a 1999 Firebird. I have been having problems lately with, starting the car. First, when I start the car it is making a grinding noise at the beginning of starting, after the car is started it's running normally(engine and sound are normal). However, after starting, all of my odometers, miles, rpms, gas gages, ect. all sky rocket very quickly and then go to normal. My odometer reading where my mileage is shows the correct mileage (overall) however, all the miles I have previous driven (before previously turning my car off the last time I had driven it) all go down to zero mileage, so I have no way of knowing how many miles I have recently driven (or how many miles to the gallon I am getting w/ gas). The only thing I can correctly see are overall milage, which appears to be correct, and stay intact after turning the car on, and off. The car is driving fine overall. However, I am concerned obviously w/ the grinding noise when starting( it's getting worse everyday), and I am concerned w/ my mileage recenting itself everytime I turn the car back on. Also, if I turn the car off w/ the stero left turned on, when I turn the car back on, the stero is now turned off, which it never used to do. It would just stay on if I had left it on the first time I turned the car off.****
I was thinking it may be the starter at first, (w/ the grinding and all) but I wasn't sure if that would effect how my gages are behaving and the stereo?? Any help would be appreciated! Thanks...:)