The House Has Gone Bust!

The House Has Gone Bust! is a side quest that is automatically failed after killing Mr. House because you cannot leave to complete it.

Walkthrough
This quest appears after killing or disconnecting Mr. House in the control room. Before this quest is completed (or failed) you will not be able to take the elevator to another floor from the penthouse. This is due to Victor being hostile towards you. Since he controls the elevator until this point and you will be unable to speak with him while hostile, this seems to be a fix by Obsidian to turn control of the elevator back to the player. The other side effect is that you are locked into the penthouse and control room until you complete (or fail) this quest.

After starting this quest it will usually be immediately marked as failed. In rare cases, the quest will be mark as completed, granting 505 XP, or even 755. However, it is currently unknown if Mr. House himself causes this XP boost or if the quest itself does.(Even though it is very obviously it is both Mr. House and the quest completion that leads to the XP boost which is why it is not 500 or 750. The excess experience comes from either a difference in level; causing Mr. House to give different amounts of experience, or a roll for three different quests with either failing or two prototype setstages that never made it. It could also be a perk boosting or lowering experience having an exceptional value where it would normally be 10% extra or less)