Idiot... I am an idiot... found the problem I forgot to change the boards to Atmega1284 in IDE last time I uploaded. thats why this time I got sync errors... I was toggling between Duemolanove and Atmega1284 so last time I forgot to change it back... SO new bootloader has actually solved the problem... 
I am so relieved now!!!
Thanx again for Nick and Crossroads for your helps... 