Freeze during boot?

Sounds like one of those quirky motherboard issues which are usually, knock wood, benign. System overclocked?
RAM set to correct voltage?

Yes my system is overclocked, but I don't think it matters because I've set everything in BIOS to defaults and I still sometimes freeze. My RAM voltage is at [auto] or something (whatever the BIOS thinks its default)

BIOS defaults RAM voltage to 1.8v but a lot of today's RAM requires higher - 2.0, 2.1, even 2.2. You need to determine what your RAM needs and then manually set it to that voltage. The voltage spec is usually written on the label on the stick itself. This has been a very common problem lately. It's a long shot that that's what is causing the hang but it's worth fixing for your overclocking potential and general system stability.

If the CPU is much overclocked it too may need more voltage, more than Intel's spec. Sometimes these voltage issues can cause components to fail to initialize at boot.

I had a similar situation with my Asus A8N32-SLI. I had damaged my board and ordered a 'used' replacement of the exact same board. When I got everything assembled, Windows XP Pro would hang at boot up right at the beginning when you see the initial Windows logo and the blue bar running around before the Welcome screen pops up. Or sometimes I would get no Windows logo at all and a message would appear saying 'unable to load OS" or something like that.

I removed my IDE slave drive so only my SATA drives were connected and then It worked. I got all the way to my desktop and all looked fine, except I didn't have my IDE drive connected. No more OS message, more hanging XP screen.

Ok, I was able to run in safe mode with all drives connected including my IDE. But then things got worse. Windows XP would hang at boot up again even when I disconnected the IDE drive. At this point the only thing that worked was Safe Mode. So I started thinking that maybe I need to re-install the OS since I changed the motherboard.

I slept on the idea of reinstalling windows. The next morning I tried to boot my computer, and it all worked. Startup was a success. Even with the IDE drive connected. I was dumb-founded. Then I decided to reboot. And the problems came right back. I could only boot up in safe mode.

SOLUTION: I read here in this thread that I need to be sure the battery on my new motherboard was good. So I swapped the battery from my old motherboard and now everything works. It's a miracle! No more OS message, No more Windows hanging during boot up. Everything is back to normal.

Note: Hey, I did have to reset the date and time on the bios as well as my boot sequence.

Hope this helps someone....