Blazer gauges read low - won't start

I have a 1995 Blazer 4x4. For a while now, the fuel and voltage gauges have read just a little higher than they should. Now, the voltage gauge reads about 3 volts low and the Blazer won't start. I have checked the voltage and even charged the battery just in case. The voltage pulls down to 11.1 volts when cranking, but the gauge reads clear down in the red. I can't help but think that these are related. Maybe the computer won't let it start because it thinks the voltage really is that low. Any Ideas?