The optical Dell mouse included in the BlueTooth package that came with my XPS 420 back in November of 2007 recently developed the following problems: 1) extremely difficult to keep text highlighted and 2) frequently a number clicked once appears twice when while using the Windows calculator. Both are the result of a double click response to a single click. I bit the bullet and disassembled the mouse to take a look. The first picture below is of the mouse before disassembly. The green circles in the second picture indicate the locations of the mounting screws. It is necessary to puncture the material at those locations to access the screws. Once dissembled, I noticed that the switches are sealed and hopefully were not the problem. I kept my fingers crossed and sprayed a bit of WD40 on the actuators for the left and right buttons in the top shell of the mouse. It took me a while to remove all of the excess WD40, but when I did and reassembled the mouse, the mouse worked perfectly and has ever since. One problem, though. It is very difficult to get the two top screws in the holes in top shell. It took a lot of trial and error, but I finally got them in. The left and right mouse buttons won't work unless the two screws are secured tightly.
The double click response has returned, although its not too bad yet. I am surprised that no one else appears to have experienced the same problem.
It's a common problem with all mice ... the main button SWITCH wears out.
You can try getting some electronic contact cleaner inside the tiny flat switch, but only way to really fix it is to solder in a new flat switch
... or replace the mouse.
Logitech gaming mice are good.
The switches in my mouse are sealed, so injecting contact cleaner is not an option. I Googled the part number that I found on the switch to no avail.
I am now the proud owner of a Logitech M705 wireless remote! It works smooth as silk comapred to my old Dell optical Blue Tooth mouse. A neat feature is that three of the four pads on the bottom of the mouse may be replaced when they ware out.