I've got a users laptop (Dell Inspiron 1100). The touchpad is active, but a mouse is plugged in and used. In my testing so far, what I have seen the most is that when Excel is open for a longer period of time, the left click suddenly takes on the properties of right clicking. This will last for a few minutes or 10 minutes and then will go back to normal. I really don't think this is a touch pad issue.
In other words, you can leave the laptop open with a spreadsheet active and do nothing and whithin some seemingly random amount of time, the properties window, as if you are right clicking, will appear and every time you left click into any cell, the right click menu will appear. Then again, this will stop after a seemingly random amount of time.
Has anyone else encountered something similar?