I realize this is an old thread, but I'm wondering if your problem has come back or not. I've been dealing with a similar issue, although the car is working fine ....now.

 

Hi
It was caused by condensation behind the dash and getting into the instrument cluster.
Kept the IC inside the house for ages drying out, and used an electric fan heater pointing at the dash (doors slightly open) off and on for days until it all seemed dry.
Since then it seems to have been ok. However, I have not started it again since the winter, I could be back to square one. But at least I know how to fix it.
Good luck.

 

Condensation, or a leak?

 

Condensation for sure. Once it was damp it was difficult to fully dry out.