It has problems with new processors on Virtual PC 2007 (especially the x64 version)

You must use VirtualBox with I/O cache disabled on both the floppy drive and the IDE HDD.

Install as you normally do with any NT 3.1 build (except Oct1991, 239.1 and 297.1 of course)

Do not install the Adaptec AHA-2940 adapter.

After the text-based Installation, apply the Pentium II and higher patch and also, replace atdisk.sys with a Non-Debug one.

You will now be prompted to go to the GUI stage of the Installation and you happily run the OS without any problems.

Optional: For higher resolution and color depth, use VBEMP.

Hmmm, so the hardcoded breakpoint in NT 3.1 chk is in atdisk ? I guess that explains some issues.

yes it is, I managed to install Build 528 Debug on VirtualBox without any problems, and I have a VHD of it complete with Sound and VBEMP and with a IDE CD-ROM Driver.

i always installed it in virtual pc thanks to com0com and i386kd 1.0

Well, this guide is for users that do not have experiences with debugging

Can you give me the link to the VHD?

once I get Build 122 Checked in my hands. And a small VHD for Chicago Build 122 Non-Debug will be available for download soon.