OS: DOS 6.22
RAM: 256MB(Hardware) / 64MB(DOS recognized)
Contents of config.sys:
device=c:\dos\himem.sys
buffers=15,0
files=30
dos=umb
lastdrive=e
fcbs=4,0
dos=high
Autoexec.bat file is almost empty with only PATH / SET TEMP lines etc.
EDIT: oh, sorry, I have enough system memory (612K).