If you can get into the machine through safe mode, you can use
start -> settings -> control panel ->administrative tools ->event
viewer
to view the system or security log. It may tell you what's stopping
your system boot.
without knowing what you've got installed, it's hard to guess what
could be wrong.
If you can't get into safe mode, it will be difficult to uninstall
anything. So hopefully the viewer will work. If it doesn't unplug
all USB devices (printers, mice, keyboards etc) and all 1394 systems.
If you have an onboard USB chip, go into hardware setup and disable
it. Disable your on-board LAN chip if you've got one.
I've seen so many of these problems, and they're all different but
usually are caused by some optional hardware interaction with the OS.
So try to disable all your optional hardware (like the LAN card).
If disabling the LAN card fixes it, you might try to rename mup.sys so
Winnt won't find it. You probably don't need mup, and I've seen it
cause numerous "just hangs".
One more thing: if you can create a boot floppy which will let you
intto your file system, the system event log is probably at
winnt/system32/config/sysevent.evt. You can use elogdmp.exe to dump
the event file to an access database file that you can read off-line.
You'll find elogdmp on the win2K resource CD. I never tried to copy
the event log to a floppy and move it to another computer to read it,
I always export.
HTH a lot. Can be very frustrating.
Rock