Hello everyone. I've tried to install Win XP Pro on my PC but, at what I think is the pre-installation phase, the computer locks and a blue screen comes up with an "ACPI" error. This only happens when I have 512MB PC100 RAM installed (2x 256 MB 168-pin modules, both have dual sided chips and are identical and manufactured by Samsung). However, on 256 MB the computer runs and installs XP without any problems whatsoever. I tried putting the other 256 MB module (to make 512 MB total) after installation but it won't boot. The bizarre thing is Win ME runs on 512 MB RAM without any problems whatsoever. The Phoenix bios on this machine is dated June 2000 and the Asus Hawk motherboard is capable of 512 MB RAM. What's happening - 512 MB supported by an older OS but not the newer?

Try with ACPI set to Off in the bios.Good luck.

Look at bios first to see if ram is read correctly. As with any OS the abiltiy to read hardware is a part of the bios. There are billions of possible reasons for this. Every chip,firmware,gate and clock on that MB can cause this. I have seen it many times where a fully working MB on one OS will not support the new OS. See if the bios has an update that address's this exact situation. Consider a fully supported XP machine. That is if the above doesn't fix it.