Pathipati,
STOP posting.
I know (or at least can make a qualified guess) that you are pulling out your hair over this. Stand back! take a breather. Now, go to the above threads

erik malund 11-10-04 08:29
through
Prahlad J. Purohit 11-10-04 08:56

from 3 sides; DO what is suggested, Do that, THEN post

A brief look at your picture (how about a schematic) show that you have NOT decoupled every Vcc with .1 to .01 uF and I even recommend that at the uC you parallel those with 10uF. The decoupling I think I see on your board outside the miniboard with the CPU is WORTHLESS. The bit of traces and the pins connecting the miniboard create enough of an inductance to allow the pin to "jump"

Erik