Random Fatal Exception Errors While Running Windows 95

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The information in this article applies to:

• Microsoft Windows 95
• Microsoft Windows 98

SYMPTOMS

Windows 95 reports random "Fatal Exception Error 0x:xxxxxxxx" error messages even though your previous version of Windows or Windows for Workgroups did not.

CAUSE

A common cause for these 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 95 may report random "Fatal Exception Error 0x:xxxxxxxx" error messages:

• All operating systems use memory differently. In Windows 3.1, the "bad" memory may be used for holding rarely used data. In Windows 95, the "bad" memory is used for holding frequently run program information.
• Windows 3.1 contains comparatively little 32-bit code. Windows 95 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 95 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 95 runs 32-bit code in all portions of memory. Therefore, when Windows 95 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 95 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."

RESOLUTION

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 95 successfully. In other cases, disabling the motherboard L2 cache allows Windows 95 to run. For information about how to edit CMOS settings, please view your computer documentation or contact your hardware manufacturer.

Note that you may want to restart Windows 95 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 information about how to troubleshoot Windows 95 using Safe mode, see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q156126
   TITLE     : Troubleshooting Windows 95 Using Safe Mode

MORE INFORMATION

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. For more information on exception errors, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q52195
   TITLE     : Exception Errors with EMM386.SYS / EMM386.EXE