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Q196611: Error Code 29 After Resuming from Suspend Mode

Article: Q196611
Product(s): Microsoft Windows 95.x Retail Product
Version(s): WINDOWS:95
Operating System(s): 
Keyword(s): kbenv kberrmsg osr2
Last Modified: 17-DEC-2000

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The information in this article applies to:

- Microsoft Windows 95 OEM Service Release, version 2.5 
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SYMPTOMS
========

After you resume your computer from Suspend mode, a Peripheral Component
Interconnect (PCI) device may appear in Device Manager with an exclamation point
in a yellow circle. When you view the properties of the PCI device, the
following message may be displayed under Device Status:

  The device has been disabled in the hardware. In order to use this
  device, you must re-enable the hardware. See your hardware
  documentation for details. (Code 29.)

CAUSE
=====

This problem occurs because Windows 95 OEM Service Release 2.5 does not
rebalance interrupt request lines (IRQs) correctly.

RESOLUTION
==========

To work around this problem, remove or disable an unused device in Device
Manager to free a system IRQ. To disable a device in Device Manager, follow
these steps:

1. Click Start, point to Settings, and then click Control Panel.

2. Double-click System.

3. On the Device Manager tab, double-click the branch containing the device you
  want to disable, click the device, and then click Properties.

4. On the General tab, click the Disable In This Hardware Profile check box to
  select it, and then click OK.

5. Click Close, and then restart your computer.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Windows 95 OEM Service
Release 2.5.

This problem is fixed in Microsoft Windows 98.


MORE INFORMATION
================

When the computer is started, Windows 95 performs a PCI IRQ rebalance to free up
system IRQs as needed. In order to accomplish this task, Windows 95 routes
multiple PCI interrupts to a single system interrupt.

Internal data structures in Windows 95 are set up to maintain information on
which PCI IRQs are routed to which system IRQs. In cases where multiple PCI
interrupts are routed to a single system interrupt, the pointer to this IRQ
routing information may be lost. Windows 95 continues to function properly until
the computer goes into Suspend mode. At that time, Configuration Manager
attempts to remove resources for all PCI devices. It cannot do so on the device
or devices that use the PCI interrupt controlled by the missing IRQ routing data
structure, resulting in that PCI device having an error code 29
(CM_PROB_HARDWARE_DISABLED).

Due to the nature of PCI interrupts and IRQ routing, this problem may or may not
be evident on a given computer based on a number of variables, including PCI
slot design (how the PCI interrupts are routed between slots), PCI card
interrupt usage, and system IRQ availability.

For additional information about PCI bus IRQ steering, please see the following
article in the Microsoft Knowledge Base:

  Q182604 Description of PCI Bus IRQ Steering

======================================================================
Keywords          : kbenv kberrmsg osr2 
Technology        : kbWin95search kbOPKSearch kbWin95OPKOSR25
Version           : WINDOWS:95
Issue type        : kbprb

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