This article was previously published under Q283063
When you are using a Windows 2000-based computer, a serial device may be detected as a serial mouse.
This problem can occur because most of the devices that are detected as serial mice that are some other type of device constantly send data to the serial port which causes the detection code to incorrectly identify the device as a serial mouse.
To resolve this problem, obtain the latest service pack for Windows 2000 and then update the registry as instructed below. For additional information about the latest service pack for Windows 2000, click the article number below to view the article in the Microsoft Knowledge Base:
260910 How to Obtain the Latest Windows 2000 Service Pack
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:
322756 How to back up and restore the registry in Windows
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:
On the Edit menu, click Add Value, and then add the following registry value:
Value Name: SkipEnumerations Data Type: REG_DWORD Radix: Hexidecimal Value: 0 through FFFFFFFE
Note 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.
Quit Registry Editor.
To work around this problem, allow the device to be detected incorrectly, use Device Manager to disable the device that is not the port to which the device is attached, and then reboot your computer. When you do this, the port works correctly and the incorrectly detected device is disabled.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 3. After you install Windows 2000 Service Pack 3, you must edit the registry as described in the "Resolution" section of this article.
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.
For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base:
265173 The Datacenter Program and Windows 2000 Datacenter Server Product
For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:
296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot
Applications may fail to initialize the GPS device once the SkipEnumerations change has been added to the registry even though the GPS is no longer being detected as a Serial mouse. This can be related to Ghosted serial devices still loading. For additional information about how to locate and uninstall Ghosted devices from mice and other pointing devices, click the article number below to view the article in the Microsoft Knowledge Base:
241257 Device Manager Does Not Display Devices Not Currently Present
Motherboard based COM Ports
First, 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
Discovering 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
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, locateand expand the DeviceID then expand the InstanceID below that. This is theDevice ID for the specific port of the Serial Card where the Value is to beadded.
For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:
249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes
Microsoft Windows 2000 Service Pack 1, Microsoft Windows 2000 Service Pack 2, Microsoft Windows 2000 Advanced Server, Microsoft Windows 2000 Advanced Server, Microsoft Windows 2000 Service Pack 1, Microsoft Windows 2000 Service Pack 2