Himem.sys missing or corrupt or unreliable memory Error
This is a common error with Windows 9x systems. The most common error messages related to this are: “Himem.sys missing or corrupt” “ERROR: HIMEM.SYS has detected unreliable memory at address 001003A4h”
Cause: Himem.sys file is a program that controls system access to RAM, and it is supposed to load with CONFIG.SYS. The error is either a result of a corrupt HIMEM.SYS file, or physical issues such as a RAM module not meeting the system board specifications.
Solution: Assuming that the file is actually corrupt, let’s overwrite it with a new file. Boot the system with a Win 9x startup disk. If the system boots properly, then it is likely that Himem.sys is corrupt or missing, or it hasn’t been configured properly in CONFIG.SYS. At the prompt (A:\>) type in “copy himem.sys C:\WINDOWS” and press [Enter]. If you encounter the problem on rebooting the system, then edit CONFIG.SYS and make sure that it contains the line DEVICE=C:\WINDOWS\HIMEM.SYS Save the edited file and reboot the system. You will have to consult a technician or replace the module(s) if the problem persists.