Prolong at Welcome sscreen

Dual core 2.2 Ghz
G31 chipset
1gb ddr2

install fresh windows xp sp2.
everything fine, but after installing driver and software, i notice that windows boot prolong at welcome screen.
i mean around 45 seconds at welcome screen and another 30 seconds at desktop without appearing icons.
after that, windows work normal
i can even play games without problem and no hanging at all.
i've scanned disk and defrag using windows built in program but no use.
already clean registery with ccleaner and remove un necessary app on start up.
no antivirus installed, firewall disabled and network cable unplug, no external device attach.

but sometimes, windows can boot normally without delay. around 10:1 (prolong boot: normal boot)

plz be advice
thanks