WWW and FTP Services Stop Intermittently and/or Inetinfo Stops with Dr. Watson Error (234551)

We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx

SYMPTOMS

When you run Internet Information Server (IIS) 4.0, some or all of the following symptoms may occur:

The WWW or FTP service stops intermittently.
Inetinfo.exe stops, which generates a Dr. Watson error similar to the following (the instruction and memory location listed may vary):
"The instruction at 0x77f7D514 referenced memory at 0x34323835". The memory could not be "written".
Click OK to terminate application.
A Dr. Watson log similar to the following may be generated:
Application exception occurred:
App: (pid=123)
When: 6/29/1998 @ 12:19:7.234
Exception number: c0000005 (access violation)

CAUSE

A DLL (typically an ISAPI DLL) that works with Inetinfo.exe has caused heap corruption.

NOTE: This issue may be caused by third-party DLLs. If you are using a third-party product that works with Inetinfo.exe, please check with that product's manufacturer to see if there are known problems and resolutions for that product.

RESOLUTION

Remove or update the DLL that is causing the heap corruption. To determine which DLL is causing the problem, use the IIS Exception Monitor.Note: When you use the Log File Analyzer, which comes with the IIS Exception Monitor, it is easier to view third-party DLLs if you select the Hide Microsoft Files check box.

WORKAROUND

Third-party applications may be implemented as ISAPI filters. In those cases, you can perform the following steps to determine if they are the cause of the heap corruption, and isolate them so they do not stop the Inetinfo process.

In the Internet Service Manager (ISM) or MMC, view the ISAPI Filters tab for the Web site to determine which files are associated with the third-party application.
Go to the appropriate Web site (or virtual directory) for those files.
On the Home (or Virtual Directory) tab, under the Application Settings section, create an application, and select the Run in separate memory space (isolated process) check box.

MORE INFORMATION

Heap Corruption

Heap corruption occurs when DLL "A" allocates an amount of memory for its use, but then writes more memory than was allocated, thus overwriting some memory actually allocated to DLL "B." Then, when DLL "B" attempts to use the memory that DLL "A" overwrote (and corrupted for DLL "B"), DLL "B" fails.

Because the error is reported in DLL "B," rather than DLL "A," which caused the problem, the problem is difficult to pinpoint.