DOS ERROR 4
please do write statements as follow in your config.sys file

FILES = 100
BUFFERS = 45

DOS ERROR 5
please select all files in folder and right click and get 'Properties' option and remove tick mark of Read-Only Attributes

Memory Trouble
If your are using DOS / Windows 95 or Windows 98 then write statements in config.sys
FILES=100
DOS=HIGH,UMB
BUFFERS=50
NUMLOCK=ON
DEVICE=C:\WINDOWS\HIMEM.SYS
DEVICE=C:\WINDOWS\EMM386.EXE NOEMS

If your are using Windows ME/2000/XP then write statements in config.nt in windows\system32 folder

FILES=100
BUFFERS=50