Weird Touchpad operation

[PeterGaven]

I have a set of new Dell Latitude E5500 laptops. They all run Windows 7 business. A couple of them have been displaying some weird behavoiur. One in particular is very bad. When it is in the teachers classroom, the touchpad is so dysfunctional that she has to use a USB mouse. As soon as she takes that machine to a different room in the school the touchpad works perfectly! When she takes it back into her room - problems again. Dell have replaced the touchpad and palmrest, the motherboard and the hdd, all to no avail. Two other machines occasionally display similar behaviour. Any ideas?

[obijon]

By "dysfunctional" do you mean the mouse cursor jumps around the screen and randomly selects or deletes text as they are typing? If so, it's probably because they are brushing the touchpad with their palm ever so slightly. Try disabling Tapping in the touchpad settings of the Dell touchpad software (touchpad icon in the system tray). When they carry their laptop to another room they may be sitting higher or otherwise changing how they use the laptop. If they must have tapping you can reduce the sensitivity of the touch later (after you've established the problem is due to tapping).