This is not a DIY diagnosis and fix...you are loking at a complete instrument cluster assembly replacement (hopefully under warranty?)
Had an '86 Cavalier Z-24 with the digital instruments that did the same thing. Pulled the entire thing out and tried to bench check it. So many things wrong, that I threw up my hands and exchanged it for a reconditioned unit ($237 back in '90). Noticed that certain components had been redesigned and realigned on the reconditioned unit. I was told that this was a manufacturers defect, but most cars were out of warranty by the time the problem surfaced...how convenient!
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car