Open config.sys with notepad

If a line that says "DOS=" already exists, change it to say "DOS=HIGH,UMB"  If it doesn't exist simply create it.

Also make sure the lines below are found at the top of config.sys, they are requirements that DOS be loaded into upper memory. 

DEVICE=C:\WINDOWS\HIMEM.SYS
DEVICE=C:\WINDOWS\EMM386.EXE NOEMS

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