as the machine is starting to boot up...
hit F8 and choose  step by step confirmation

be sure to start a bootlog.txt

for starters  do not process  autoexec.bat and config.sys
but say "yes" to all to choices

if windows starts ok...

you can just rename autoexec.bat and config.sys
as windows does not need them

if you still have problems

try safe mode

and lastly command prompt

if you examine the bootlog.txt file you may see what has failed to load.

post back the results