Peripheral Component Interconnect: A computer bus for attaching peripheral devices to a computer motherboard.

On a computer that runs Windows Vista or Windows Server 2008, a Peripheral Component Interconnect (PCI) Express bus may run in PCI compatibility mode instead of in PCI native mode after the PCI root bus restarts. For example, the PCI root bus restarts when you disable and re-enable the root bus in Device Manager. Therefore, all PCI Express-related functionality, such as Windows Hardware Error Architecture (WHEA) and power management, is turned off.

When you remove a Peripheral Component Interconnect (PCI) host CPU bridge from a Windows Server 2008-based computer, you receive the following error message in the System log:

Log Name: System
Source: PlugPlayManager
Event ID: 12
Level: Error
Description: The device 'PCI standard host CPU bridge' (PCI\device ID) disappeared from the system without first being prepared for removal.

Consider the following scenario. You have a PCI multiport serial adapter from Connect Tech, Inc. installed on a Windows Vista-based computer. You have a device connected to this PCI multiport serial adapter. In this scenario, a black exclamation point (!) on a yellow field appears next to the device in Device Manager.

Note: An exclamation point in Device Manager typically means that either the device or the device driver is installed incorrectly. Or, the device or the device driver is not working correctly.

When you connect a PCI ExpressCard device to a portable Windows Vista-based computer, the device may not work correctly. A yellow exclamation mark may appear next to the device in Device Manager.