Really can't say why it would suddenly change to not working. Would it be possible to use something like a desk blotter or large calendar under both the keyboard and mouse so it works right? Something that isn't so tacky as a sheet of paper and yet accomplishes the task?
I have had inconsistent optical mouse behavior on a number of very shiny surfaces so know what you are talking about, but have not found a solution other than some thing like a mouse pad or paper, or such under the mouse.
I understand what you are trying to do, don't have a solution other than to say be creative...there has to be something that will be clean and uncluttered, make the mouse work, and meld in with the image you want to project. I wonder if there is some kind of less reflective surface that could be used on the granite, something that dulls the surface. Just thinking out loud.
Thanks for the info, but I can't change my desk. What's really strange is that it had been working BEAUTIFULLY for the first few days. Then yesterday, all of a sudden it decided it hated granite.
Currently using my iPad (covered) as a mouse pad. I have to admit though, it looks like poop.
wireless optical mice,either laser led or older or newer tracking technologies, still have issues with very glossy surfaces.
Here's something creative you could try.
Use a digital camera with no flash, take a picture of the granite surface.
Import into your iMac using iPhoto and print it out on sone heavy weight matte paper.
You may have to edit the image to get it as close to the real granite top as possible.
So, print this out on some regular ink jet paper first.
Use a 8-1-2 "x 11"sheet to print out the image. Cut the sheet to a size you think would be fine as a working area for the mouse (say a 6" x 6" or 8" x 8" area)
Locate the area you took a picture of and lay the sheet in place until you find the exact area.
Mark the edges with some masking tape.
Then use double stick tape on the back of the sheet and tape in down to the exact place you took Yhe original image.
You now have a flat, non glossy image of the granite desk area to run your Magic Mouse on.
It wasn't a joke.
Don't knock an idea until you try it!
You wanted something that would blend with your table?
This will definitely do the job.
I have actually done this in my parents' kitchen which has light colored, glossy granite counters.
I stood on a small ladder and took a straight down digital picture of an area of the counter top.
I did some image editing to get it to look right and printed the result to a heavy weight matte paper that I mounted to the counter using double stick tape on the back of the sheet on every edge to seal it down to the counter top.
To make it kitchen proof, I sprayed the image sheet with a sprayable artist clear matte coat to make it somewhat waterproof.
Blends in nicely. I have to replace this maybe once a year as it gets somewhat beat up during the year since this area is near the main cooking/work area, but you don't have that situation.
I just remembered I took the digital picture at an angle that minimized unnecessary reflections. Especially the reflection of me with the camera. Just make sure you take the picture without using the camera's flash.
Any good point and shoot digital camera will work.
If you want to take the time to try this, this would be a pretty good solution.