someone had a similar problem, heres a link to the thread.
http://bmwboard.com/forum/showthread.php?t=7691
and this was the solution posted by JohnSac
"--------------------------------------------------------------------------------
The pixels in your instrument cluster have malfunctioned. It is a common problem with these cars. You can call BMW,NA at 201-573-2188 and ask for Chuck Winik, or E-mail
Leonora.vlaovich@bmwna.com. BMW,NA is currently replacing the clusters, with many owners paying for the labor at the dealership. One-half to one hour maximum for the replacement of the unit. I believe that they have handled thousands of these claims. On this and other boards I have only read of the above taking place. Make sure that they don't try to get you to pay for anymore than above. Good luck."
and the girl only paid 64 $ to have it replaced