Computer Stops or Hangs Due to Large System Environment Variable Values

ID: Q223275

The information in this article applies to:

SYMPTOMS

After adding an environment variable that contains a large number of bytes, the computer will not restart.


CAUSE

Certain process start up code for system processes (CSRSS, Autochk) were only allowing 512 bytes of space for system variables, which caused memory to be overwritten.


RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Windows NT 4.0 service pack that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp
The English version of this fix should have the following file attributes or later: 

   Date      Time                 Size    File name     Platform
   -------------------------------------------------------------
  3/25/99     7:35p               429,840  Autochk.exe  (x86)
  3/25/99     7:39p                 7,440  Csrss.exe    (x86)

  3/25/99     7:33p               669,456  Autochk.exe  (Alpha)
  3/25/99     7:35p                12,048  Csrss.exe    (Alpha)

NOTE: If this product was already installed on your computer when you purchased it from the Original Equipment Manufacturer (OEM) and you need this fix, please call the Pay Per Incident number listed on the above Web site. If you contact Microsoft to obtain this fix, and if it is determined that you only require the fix you requested, no fee will be charged. However, if you request additional technical support, and if your no-charge technical support period has expired, or if you are not eligible for standard no-charge technical support, you may be charged a non-refundable fee.

For more information about eligibility for no-charge technical support, see the following article in the Microsoft Knowledge Base:
Q154871 Determining If You Are Eligible for No-Charge Technical Support


STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0.


MORE INFORMATION

The new files in this hotfix increase the number of bytes to 4,000. Users should keep the total system environment variable size to 4,000 characters. This size also included the variable name.

Additional query words: 4.00 


Keywords          : kbbug4.00 kbfix4.00 
Version           : winnt:4.0,4.0 SP4
Platform          : winnt 
Issue type        : kbbug

Last Reviewed: July 2, 1999