possible reasons:
1. when you precooked the rice you used too much water and it came out too sticky (i hoped you precooked the rice ;)). this canbe solved by washing the rice well before cooking and using less water and very low heat when cooking.
2. the oil wasnt hot enough before frying. dont use to much oil and make sure its very hot before putting in the rice.
3. the rice should be fried for a very shot time, if the oil is very hot one minute should be enough