try re-installing your driver for your sound card just to reset things.
sometimes it works..sometimes it doesnt.

just give it a try.

is it a wireless usb mouse? maybe the batteries are dead?
if not..try inserting it to the other sockets and see if its working.

last resort is to return it. just make sure you
have your...

Call Dell's Customer's Service. they can provide you a great deal if you purchase in large quantity. Try also the big electronics shops, maybe they can give a good deal as well.

maybe you can try to... clean it with sandpaper..?! just to get rid of the
grime in it..

just give it a try though.

it usually comes with the CD... in case you dont have it,
locate the model number of the unit., usually at the back
or at the bottom. then paste it on to google and download
the driver...

try using a different mouse.., maybe the mouse is defective of some sort...