Bad RAM Causes Fatal Exception Errors Running Windows 95/98

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Article ID: 138788 - View products that this article applies to.
This article was previously published under Q138788
If this article does not describe the error message that you are receiving, view the following Microsoft Knowledge Base article to view more articles that describe error messages:
315854 Windows 98 and Windows Me Error Message Resource Center
If this article does not describe your hardware-related issue, please see the following Microsoft Web site to view more articles about hardware:
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Windows reports a random "Fatal Exception 0x has occurred at xxxx:xxxxxxx" error message even though your previous version of Windows or Windows for Workgroups did not.


A common cause for this error messages is faulty physical memory (RAM) on the computer. The following are reasons why your previous version of Windows may appear to run smoothly while Windows may report a random "Fatal Exception 0x has occurred at xxxx:xxxxxxx" error message:
  • All operating systems use memory differently. In Windows 3.1, the "bad" memory may be used for holding rarely used data. In Windows, the "bad" memory is used for holding frequently run program information.
  • Windows 3.1 contains comparatively little 32-bit code. Windows uses much more 32-bit code. Furthermore, there are subtle differences between the way memory is accessed if it is being accessed for code or if it being accessed for data. Because Windows runs much more 32-bit code, these subtle errors show up more often.

    In particular, all the 32-bit code in Windows 3.1 resides in one place: at the low-end of physical memory. If the first 4 megabytes (MB) of memory can handle 32-bit code, Windows 3.1 works without errors. This is true even if the topmost physical memory cannot run 32-bit code because Windows 3.1 does not run 32-bit code outside the first 4 MB of RAM.

    Windows runs 32-bit code in all portions of memory. Therefore, when Windows runs 32-bit code in a section of RAM that cannot run 32-bit code well, you may receive "Fatal Exception Error 0x:xxxxxxxx" error messages.
  • Windows interacts with hardware differently than previous versions of Windows. This is due partly to Plug and Play and partly to new drivers that take advantage of the additional capabilities of interface adapters. These features may uncover anomalies in the hardware that never appeared in previous versions of Windows because earlier versions did not attempt to exploit these features.
  • Many new computers do not have memory chips that perform parity checking; therefore, you may have been encountering parity errors in Windows 3.1 without realizing it because the errors were in relatively harmless sections of memory. For example, in a Microsoft Word for Windows document, the word "the" is changed to "tie."


To resolve these errors, it is often necessary to replace the RAM and/or system board (motherboard). In some circumstances it may be possible to alter CMOS settings, such as Memory Wait States, to run Windows successfully. In other cases, disabling the motherboard L2 cache allows Windows to run. For information about how to edit CMOS settings, please view your computer documentation or contact your hardware manufacturer.

For additional information about how to identify if your issue is faulty RAM, click the article numbers below to view the articles in the Microsoft Knowledge Base:
181862 Specifying Amount of RAM Available to Windows Using MaxPhysPage
134503 Parity Error Messages May Indicate Bad Memory
Note that you may want to restart Windows in Safe mode to see if the errors persist. If they do not, the problem may be a software or driver problem, in which case the information above may not apply. For additional information about how to troubleshoot fatal exception errors, click the article numbers below to view the articles in the Microsoft Knowledge Base:
192926 How to Perform Clean-Boot Troubleshooting for Windows 98
156126 Troubleshooting Windows 95 Using Safe Mode


Fatal exception errors are similar to EMM386 exception errors. For example, fatal exception error 0C is generally equivalent to EMM386 exception error 12 or a stack fault.


Article ID: 138788 - Last Review: January 19, 2007 - Revision: 2.1
  • Microsoft Windows Millennium Edition
  • Microsoft Windows 98 Second Edition
  • Microsoft Windows 98 Standard Edition
  • Microsoft Windows 95
kbdiskmemory kberrmsg kbfatalexerr0d kbfatalexerr0e kbhardware kbprb KB138788

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