Hi grofaty,
Thanks a lot.....its working!
but one thing i am not getting is, how this worked till date, i mean, i was aware that the host name was changed for the system on which my db2 server resides but was not aware that i need to make changes in the config file also and so i din't made any changes in the config file. still it was working n suddenly i faced problem today though i changed the host name a month back.