Hitachi 43in. projection tv model# 43GX10B 2002

The color has gone crazy on you because your convergence IC's have gone bad.
These operate at a very high temp, and usually only last 4-5 years. 
If you remove the back of the set, you will want to look for the BIGGEST heatsink in there, on that heatsink, you will see 2 lage IC's , probably STK392-110, or STK392-150's you can go on ebay to order the new ones, but MAKE SURE they are Genuine SANYO IC's and not counterfiet cheapies. the cheap ones may only last 2 months..
You will also need some "Heat transfer paste" - you can pick this up at radio shack.
Once you remove the old IC's, test all the large resistors near them.. pull one side of the resistor out of the board so you can check it out of circuit. they will usually have the value in Ohms, printed directly on the resistor, but you may have to use the resistor color code to find out what value they are....However, usually if there is any damage, the resistor will look like it has been HOT or fried. replace the IC's and any bad resistors, and you should be good to go.
If after replacing the IC's and any defective resistors, the convergence is still bad, make sure to use a multimeter to check ALL fuses on the boards, --- sometimes when the IC's go, they will take out a fuse to the convergence power supply. If you find any bad fuses, replace them accordingly!
Hope that helps!