No display on my monitor only after first boot

This is allen from india. I have a Gigabyte GA-G31-MS2L MoBo powered by a dual core processor!!
Recently i bought a new radoeon HD 3650 512 mb DDr2 graphics card for my pci express MoBo! I had onboard intel G31 graphics
for the past 4 months so i went for this mainstream card!! But sooner i faced a troublesome problem with it!! It would be nice if i can get some help.
The problem is....
I fitted the graphics card after i disabled the onboard graphics in my bios..then i booted the system it works fine without
the drivers installed.But as soon as i had installed the drivers, i come across this probelem...
as soon as i load xp sp2 my 19" lcd automatically recieves no power signal from my GPU at the WELCOME screen. but my OS loads without prob as i can hear
the loading sound.This happens only during fisrt boot after switchin on the main supply or after a shutdown, i try to restart. Othewise if i restart or
load after entering in to the bios, i have no problem..a second restart always works!! once i enter xp all the games are runnin fine..but for this loading prob!!
can i have a solution....i wud appreciate!!
Thank u