Left mouse button acts like the right mouse click due to mouse configuration.
The mouse is currently configured to be a left-handed mouse.
Double-click the 'Mouse' icon. Click the 'Buttons' tab. Select the 'Right-handed' radio button.
1) Click the 'Start' button to display the 'Start' menu.
2) Select 'Settings' and select 'Control Panel'. (The 'Control Panel' window appears.)
3) Double-click the 'Mouse' icon. (The 'Mouse Properties' dialog box appears.)
4) If necessary, click the 'Buttons' tab.
5) Select the 'Right-handed' radio button in the 'Button Configuration' group.
6) Click 'OK' to close the 'Mouse Properties' dialog box.