Why is the mouse pointer displayed in two-dot unit when movement is in the vertical direction?

When moving the mouse pointer in vertical direction, the ordinate of mouse pointer reads 2 dot while the ordinate of application reads 1 dot.

This symptom is not related to the pointing device, such as mouse or touchpad. Furthermore, it only happens in Windows 2000 and Windows XP.

Please follow the steps below to reduce the Graphic Hardware Performance Level to resolve this symptom.
1. Click Start, point to Settings and click Control Panel.
2. Click Appearance and Themes and click Display.
3. Click Setting and click Advanced.
4. Click the Troubleshoot and reduce the Hardware acceleration to a lower setting.

Note: Reducing the Graphic Hardware Performance Level into a lower setting is to disable cursor and bitmap accelerations. This may be helpful in solving some common mouse pointer problems.