The English-language version of this fix should have the following file attributes or later:
Date Time Version Size File name
1/17/2001 03:48p 5.0.2195.3156 13,936 Serenum.sys
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
After you apply the hotfix or the service pack, follow these steps:
- Start Registry Editor (Regedt32.exe). To do this, click Start, click Run, type regedt32 in the Open box, and then press ENTER.
- For instructions on how to identify the Enumerator, DeviceID, and InstanceID for your COM Port refer to the More Information section below:HKEY_LOCAL_MACHINE\System\CurrentControlSet\Enum\Enumerator\DeviceID\InstanceID\Device ParametersNote that there is one InstanceID for each port.
- On the Edit menu, click Add Value, and then add the following registry value:Value Name: SkipEnumerationsNote that a value of zero (0) disables the feature and device detection can resume. Each time that Plug and Play does an enumeration, it counts down one, and when it counts down to zero, it re-enumerates the hardware and then starts counting down again from the registry value. When you reboot the computer, Plug and Play starts the count again at the value that you typed.
Data Type: REG_DWORD
Value: 0 through FFFFFFFE
- Quit Registry Editor.
Note that Microsoft Windows XP also includes the fixed Serenum.sys file; you must edit the registry as described in the "Resolution" section for Windows XP also.
Motherboard based COM PortsFirst, you need to determine which HAL is being used before you can make the registry change. To determine which HAL is running on the system open Device Manager and expand Computer.
If the system has an ACPI HAL you can add the SkipEnumerations Reg_DWORD Value shown in Step 3 above to the serial port of choice located under
NOTE: Port# = InstanceID
COM Ports on Serial Port Add-On CardsDiscovering the correct location in the registry for the port is more involved. Below is a method that will help to you locate and identify each component.
- Open Device Manager and view the Com Port's Device Description, or "Friendly Name".
- Locate the Setupapi.log in C:\Winnt and search the setupapi.log for the Device Description, exactly as it appears in Device Manger, of the Device hanging off the Port in question.
- Once the device is located in the setupapi.log slowly scroll down until you locate the entry "Doing copy-only install of Enumerator\DeviceID\InstanceID." For Example: Doing copy-only install of MF\PCI#VEN_131F&DEV_2052&SUBSYS_2052131F&REV_00\3&1E67C166&0&50#CHILD0003
Enumerator = MF
DeviceID = PCI#VEN_131F&DEV_2052&SUBSYS_2052131F&REV_0
InstanceID = 3&1E67C166&0&50#CHILD0003
NOTE: The SkipEnumerations Reg_DWORD Value is to be added under the \Device Parameter's Key for each particular InstanceID.
- Open regedt32.exe and expand HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum5. Expand the Enumerator, locate and expand the DeviceID then expand the InstanceID below that. This is the Device ID for the specific port of the Serial Card where the Value is to be added.
When you attach a device to a serial port on a computer that is running Windows 2000 and reboot the computer, the operating system enumerates devices and looks for new or removed hardware when the computer starts. During this detection phase, the computer detects the serial ports and tries to determine what type of device is attached. Typically, the software detects a serial mouse as attached when it is some other type of hardware device, such as a Global Positioning System (GPS) devise.
- Expand the Enumerator, locate and expand the DeviceID then expand the InstanceID below that. This is the Device ID for the specific port of the Serial Card where the Value is to be added.
Article ID: 283063 - Last Review: Mar 15, 2008 - Revision: 1