In my experience, that's an unsolvable error. The only solution I have found for it is to restore a contacts backup that does not have it and re-enter the contact. Hopefully someone else has a solution and we can both learn from it.
I had that issue with a contact that was sent thru BBM. When I upgraded to 5.0.975 the problem went away. I'm assuming because it restored the contacts backup. Other than that, I didn't see any other solutions.