PS/2 Wheel Mouse Causes Cursor to Jump Around Screen

This problem occurs when then internal touchpad does not have a wheel or scroll function but the external mouse does. The wheel mouse transmits in 4-byte packets, while the internal touch pad transmits in 3-byte sequences. PS/2 devices are designed in such a way that the operating system may not be aware of an additional pointing device, nor of what the packet boundaries are between the different devices.

If the operating system interprets the packet alignment incorrectly, it may misinterpret data, thus causing erratic movements and clicks.

Choose one of the five workarounds:
1. Use the Auto Disable feature of the BIOS
2. Disable the PS/2 mouse wheel
3. Connect the PS/2 mouse after Windows is running
4. Use the Fujitsu HotKeys to switch between internal or external mouse
5. Follow Microsoft Knowledge base article 282753

Step-by-Step Instructions:
1. Use the Auto Disable feature of the BIOS
       1. Set BIOS Keyboard/Mouse Features as explained in the BIOS Guide to:
               1. Internal Pointing Device : [Auto Disabled]
               2. Infrared Mouse : [Disabled]
               3. Save settings and exit
                        The computer will automatically detect when the PS/2 mouse is attached and disable the internal mouse

2. Disable the PS/2 mouse wheel
        1. Open Control Panel and then double-click the Mouse icon
        2. Select the Hardware tab and then click [Properties]
        3. Select the Advanced Settings tab and set Wheel Detection to Detection Disabled
                  The PS/2 wheel will not scroll by rolling after making the change; however, clicking with the wheel then moving the mouse will scroll

3. Connect the PS/2 mouse after Windows is running
        1. Set BIOS Keyboard/Mouse Features as explained in the BIOS Guide to:
                 1. Internal Pointing Device : [Always Enabled]
                 2. Infrared Mouse : [Disabled]
                 3. Save settings and exit

         2. Only attach the PS/2 mouse after Windows has started
4. Use the Fujitsu HotKeys to switch between internal or external mouse
         1. Set BIOS Keyboard/Mouse Features as explained in the BIOS Guide to:
                 1. Internal Pointing Device : [Manual Setting]
                 2. Infrared Mouse : [Disabled]
                 3. Save settings and exit

         2. Use the FN+F4 HotKey combination to enable and disable the internal mouse
                  When the internal mouse is disabled, the PS/2 mouse will work
                  Do not use the PS/2 mouse or unplug it when the internal mouse is enabled

The Microsoft Knowledge base article http://support.microsoft.com/default.aspx?scid=kb;en-us;282753 describes creating separate hardware profiles for the touchpad and PS/2 mouse.