Kubica vs Heidfeld Crash - Euro Grand Prix

I don't understand how some people, including Heidfeld himself, can claim the crash was Kubica's fault... I understand Heidfeld's frustration (after all the tour was on his German soil and was nicely overtaken right from the start), but hitting his own teammate and then claiming it was not his fault doesn't seem right. But maybe some experts here could share their views..

It was Heidfeld's fault. Martin Brundle even said Heidfeld could/should have been penalised for it.
Heidfeld made another stupid mistake later, maybe he was having a bad day - its not his normal behaviour.

Shame, I always liked Heidfield, now I dont know what to think, and his post-race comments blaming Kubica :(.