The episode where he smashed Wilson's posters seemed out of character to me too. It would have been a great storyline if House had turned out to have a brain tumour.

So true, a tumour from the use of the experimental drug, for instance, or a pheochromocytoma causing an upsurge of adrenalin resulting in severe irritability, rage outbursts, and emotional instability. Heck, we could have had some awesome H/W as Wilson recognized it, diagnosed House and tried to convince him that something was wrong with him beyond being angry over being dumped by Cuddy. It would even explain his crashing into Cuddy's house because it was such a sudden, impulsive, uncharacteristic raging behaviour for him. The writers could have actually made some sense out of he nonsense but decided to make things worse and assassinate House's character at the same time.