Error while uploading the program- Help Us

Hai
I am having trouble with progrramming my Arduino atmega168 serial.
when i am trying to program, it shows

avrdude: stk500_getsync(): not in sync: resp=000
avrdude: stk500_disable(): protocol error, expect=0
14, resp=0*51

what we have to do...???
we are in the middle of our project, wifi robot, and when our wifi router is connected to arduino, the receiver led glows permanently and no expected output is obtained..
please help us as soon as possible...
arjun_janan@yahoo.co.in