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