Go into Device Manager andclick on the Plus sigh to the left of the mouse icon. Cliick on Uninstall and then restart your computer. That should reinstall your Mouse Driver software when the computer Restarts. Might resolve your issue.
Newer computers, You can find Device Manager by clicking on Start and then Control panel.
Older computers, click Start and then Run and type Cmd in the box and hit enter. In the command prompt window, type Devmgmt.msc and hit enter