When you are running Windows 95, you may receive frequent
(every 10 or 20 minutes) "Parity Error" messages on a blue screen. When you
receive such a message, you must restart the computer.
Parity errors are usually caused by defective memory chips
in the computer. For more information about parity errors, please see the
following article in the Microsoft Knowledge Base:
Parity Errors in Windows 3.x
Parity errors can also be caused by:
- Mismatched RAM. That is, mixing different types of SIMMs
(such as parity and non-parity RAM) on the motherboard.
- Incorrect RAM for the motherboard. For example, non-parity
RAM on a motherboard requiring parity RAM.
- Non-proprietary RAM on a motherboard that required
There are two methods you can use to identify whether
defective memory chips are causing the problem:
- Remove or replace memory chips in the computer to see if
the problem is resolved.
- Try limiting the amount of memory that Windows 95 uses. To
do so, follow these steps:
- Use any text editor (such as Notepad) to edit the
- Add the following line in the [386Enh] section of the
where <nnn> determines the amount of memory you want
Windows 95 to use.
To limit Windows 95 to the first 16 MB of memory,
add the following line:
To limit Windows 95 to the first 8 MB of memory, add the
To limit Windows 95 to the first 4 MB of memory, add the
- Save and then close the System.ini file.
- Restart your computer.
For additional information, click the following
article numbers to view the articles in the Microsoft Knowledge Base:
How to Use a RAM Drive to Troubleshoot Memory
Bad RAM Causes Fatal Exception Errors Running Windows 95/98
Defective memory chips may not be detected by memory
checking tools. Some memory checking programs are not adequate tests because
they do not test RAM in the same way that Windows uses RAM. Most memory
checkers use read/write cycles when scanning memory. Since Windows is executing
code from memory, it uses execute cycles. Execute cycles are different from
read/write cycles and are more vulnerable to parity errors. It is possible for
memory checking programs to find parity errors if the memory is extremely
faulty. Bad memory chips can also cause the following situations:
- Fatal Exception errors
- Himem.sys load failures in normal or Safe mode
- Random lockups
- The computer may stop responding (hang) as soon as you turn