hi adi
TWI always seems to be tidious till the time you won’t understand its each and every line properly.. both stayed low means there is no exchange of data.. try to make them more syncronize they are not syncronised yet so you getting this kind of problem…
there i am sending you link which might be helpful for you check out:
http://www.engineersgarage.com/embedded/avr-microcontroller-projects/atmega32-twi-two-wire-interface