When my mac hook up on projector, mouse pad does work

It sounds like you turned off your track pad. On some laptops there is an indentation on the pad to turn on and off and some have buttons on the laptop. Did you go into your track pad properties to see if it is on? You can do this by clicking on the mouse on the lower left corner of your laptop or by going into control panel. I hope this helps.

mabe a short in the keyboard/mouse wiring

They (Apple) might be right. It could be that the projector is damaged, like the bulb, or it could be incompatible with your computer, but I don't think that is the case. Try taking the projector to a computer repair place.

Reboot your computer while holding the space key, which will reset the devicetree in your mac.

try using the FN key with the monitor/VGA output selection changer(usually F5). You will see a little icon that looks like two monitors. Mouse control may have been changed to the external monitor connection. See if pressing FN(function) and holding that key and then pressing the monitor key will bring back your mouse indicator. You may need to do it with the projector connected and on.

Mine did that too. Did you recently hook it up to a projector? That seems to be what triggers that reaction on my mac. Anyway, the 1st time that happened, it went away after a couple days. Now, it's happened again, and I went into system preferences and changed the resolution. It has fixed the moving problem, but the icons are still bigger. I'm still working on it.
Hope this helps!

For these types of projectors if you're planning to hook it up using you MacBook ;

You will need a converter ( from VGA to DVI )
Using the VGA cable that came with the unit when purchased ;

Connect the VGA cable on the back of the Projector and on the other of the cable you will connect the converter ( VGA TO DVI ) since for MAC systems it has DVI ports for monitors not VGA...

You can purchase the converter at any Mac store or any computer shop near you..

lb 20u does not support mac os,yet try the auto setup on the remote , if u are getting the image properly

where can ifind mac version of kensington pocket mouse?

the best thing you can do is hook a wireless keyboard and mouse to your laptop. That's what i did and all is working well