Random freezing on the startup

I recently built a system, got it up and running installed windows vista just fine. But sometimes on the startup my system would just freeze loading into vista. Theres no sound no warning, it would sit there no matter how long i wait. It doesn't happen too often (froze on me 3 times this week) but i'm afraid there might be something wrong that can lead to a bigger issue. Its a new system so i'm still tweaking it, i don't know what the issue might be. Heres my setup:

Intel Q6600 (OC to 3.0, 9x @333, vcore @1.375) V1 Thermaltake CPU fan
EVGA F790i ultra mobo
4g Corsair XMS3 1600mhz
XFX Geforce GTX285
4HDD:
2x 74gb WD raptors in raid 0
1x 320gb maxtor
1x 35gb WD raptor
700w PSU by rockfish
CM comos S box

I have my suspicions it might be my raptors in raid 0, but i'm not too sure. This is my first time using a raid configuration. I'm also thinking it might be the mobo shortening out. When i first installed everything it would not post, "no signal" on the monitor. I untighten the mobo screws and wala it worked. Or, it might be my PSU. Its not the greatest but it works... i plan to replace it with a 1000w corsair double rail PSU soon. As far as temperature goes, i usually have speed fan up and most of my components are at 30ish C. So i honestly have no clue what the problem might be. Like i said, it doesn't happen often i can leave my computer on for 6-8 hours just fine. Just at the start up rarely it would freeze. Anyone have a sugestion or clues what it might be? I rather take care of the issue before it gets outta hand.