Well

After lots of headache and thinking. here is the information to all of you.

read all then say anything

Nokia N900 PR 1.2 has no bugs regarding Nokia messaging. It is the change and update of Nokia messaging server which showed this abnormal behavior

I thought it was N900 fault or bug before but then i signed up for the new account on Nokia messaging on My E63. The server address that i got was brandnew and it seems they moved to a bigger capacity servers as number of servers has reduced.

Anyway with new account i attempted the Nokia messaging setup on my 3G and it is working since then for past 1 week without any problem.

the problem was with nokia messaging servers changes.So try it.