Windows XP Right Clicks Automatically

For some reason, no matter what I am workiing on, WIndows XP will automatically right click. I am not even touching the mouse. I will not even be using the computer, but the right click options will pop up. Is this a bug in Widows XP. We have 500 users here and two other people report the issue. Has anyone ever seen this issue? I replaced my mouse and updated the driver, but it didn’t help.