I currently have a Celeron 2.4 GHz and I have XP PRO SP2 installed on it. I went to a shop and bought myself an AMD Athlon 64 X2 3800+ (dual core) with an ASUS A8V Deluxe motherboard and 1GB of RAM.

I got it home, assembled it, connected my "old" hard disk which I used on my Celeron, and everything works (BIOS and display and keyboard all works) but when it starts booting Windows, computer just reboots. I can choose to boot it in Safe Mode, Normal mode or Last working configuration, and all will cause the same reboot. If it goes into safe mode, I can see it trying to load vax347b.sys, and after that it reboots. I don't see any messages written after that one (giving me an option to skip loading it). Even if I press ESC and skip loading that file, it reboots. But if I connect the hard disk back to my Celeron (I'm using it right now) it boots normally and everything works as it used to.

I updated the BIOS with the latest release from the ASUS site. Also, BIOS is recognizing my hard disk, as well as my DVD RW and my CD ROM.

What is the problem here? Why won't it boot? I used to do this same procedure when I switched from my Pentium 2 to my Celeron without troubles.

On a side note, I assembled about 20-30 computers in my life, so these things are not new to me. I've got my PATA disk connected properly to IDE Primary and it's set as Master (as it was on my Celeron).

That file seems to be related to Alcohol120%. I've read forums where they recommend deleting the file from Windows/drivers or at least renaming the file to something benign like vax.txt just to see if you can boot.

Trying to boot an old hard drive to a new system can be problematic because the hardware is different. You need to boot from the XP CD and reinstall the OS on the new machine so the proper hardware config and drivers are installed.

There is a nice quick and dirty fix to this.
Rather than a full reinstall, as Scott suggested, you can do a repair.
This will have the same effect, installing all the drivers you need.
I have done this on a number of occasions.
With one HDD I went from a P3 733 to a 550 Celeron to a P4 2.8 and it works like a dream.

Thanks a lot guys.

I think I'll try the Alcohol 120% file first, then do the "repair" thing and if it doesn't work out, I'll have to reinstall everything.

I'll make sure I report back what helped, as soon as I find some time to play with it...

There... after renaming the file - nothing happened.

After doing a "Repair" I was left with a "blue screen of death" saying "STOP 0x0000007E"... I googled for it, and did what Microsoft said, but nothing helped.

I made a clean Windows install (formatted the partition) and now everything is fine.

Thanks guys!