you may want to look at www.e38.org
on the pixel problems/solutions.
I've got the same issues, whenever the weather dips below 22c my dashboard pixils (ie. ck control panel, outside temp, odometer, etc) are crystal clear. However when the weather goes above 23c, my pixels fade and columns disappear. Besides replacing entire dashboard cluster not much else you can do; go figure
On my climate control system, the temp readout on the passenger side are complete gone. My driver side temp readout is ok but noticed today 2 columns of pixels are missing.................