arduino uno bootloader problem

hi,
im using arduino uno Atmega328p-pu.. im new to ardunio uno... when i using first time i got bootloader error.. im already instal driver all the thing... now device manager also shown arduino in com port, and i have selected com 6 as arduino connected usb ,i choosen arduino uno in board and selected arduino isp in programmmer.. i done al the things correct even when click bootloader it take some time and shown following error
avrdude: stk500_getsync(): not in sync: resp=0x00
i need solution for this... pls take me get out of this prob..............

I have the same board and it does that occasionally, I find that if i reset the arduino and then upload straight away then it works fine,

its almost as if the current program on the arduino is running and prevents upload, or maybe the auto reset didnt work when you tried uploading,