To fix this problem, first determine which firmware version is installed on your keyboard. To do this, install and run the Mouse and Keyboard Center. From the Mouse and Keyboard Center Support menu, select Device information. Find your Microsoft Ergonomic Keyboard in the list, look for the firmware version listed, and then follow the instructions for your version below.
Firmware version 0106
Keep the Mouse and Keyboard Center installed. With Mouse and Keyboard Center version 13 or later, the firmware will automatically fix the problem and optimize your keyboard's performance.
Firmware version 0100
When using the number pad on Microsoft Ergonomic Keyboard, you might need to switch to an English input method for the open parenthesis "(", close parenthesis ")", and equal sign "=" characters to appear on screen as they’re typed. To do this:
Select Start > Settings > Time & Language > Language .
Select Add a language.
Enter English, select English (United States), select Next, and then select Install.
Press Windows key + Space to switch to English (United States).
Use the keys on the number pad as necessary.
Press Windows key + Space to switch back to the local language.