We got Hearthfire on the xbox 360 when it was released. My boyfriend built his house in Falkreath, furnished it and everything. Phantom items are appearing at the workbench, and once made, are nowhere to be seen.

But that's not the big problem.

The big problem is that there seems to be a timed crash each time he's in the house. I was able to enter his house from a balcony door, I went to the left to activate the mannequin, then I activated the small wardrobe beside it, then I ran to the bedroom and activated the chest, took something random from it, then strode back to the door, but didn't exit. I then walked away from the xbox for about 4 seconds to call him, and when I came back, it had crashed. I tried again and the same thing happens, whether I'm activating things or not. It seems to be about 20 seconds with everything working fine, then it crashes - music stops and everything.
Things outside the house are fine. I was able to run around the house with no crashes or anything, I was able to run off, run back, and everything was fine. Fast travel was fine and entering buildings elsewhere gave no issues. It's just a timed crash within the house in Falkreath.
I've built my own house in my game in The Pale, and have so far not experienced anything.

I've seen mention of similar problems with Hearthfire, so I'm quite certain it isn't just us. He's able to retrieve the weapons he stored to be able to carry more from his original home in Breezehome if he's quick enough, but if, for example, he stored something in the cellar, the timed crash usually goes off before he even gets there, regardless of which door he enters from, and if he jumps on the dining room table.

Has anyone else experienced similar problems? I've heard mention of a bow causing crashing upon entering the house, but the bow seemed to play no part in this.

It's the xbox i doubt it's Hearthfire, Is the xbox to hot?

Nope, the xbox isn't hot at all, it's completely fine. The xbox does crash from time to time, but when it does it's always the same way: music still playing in the background, xbox refusing to turn off when the button is pressed. In these cases, the xbox is cool, even freshly turned on in the morning and it was happening, the music completely stops, but the xbox obediently switches off as if nothing was wrong.

It only happens within the house, regardless of where in the house you are, after a short period of time, regardless of what you're doing, it crashes.

have you tried re-installing the game? sometimes that helps with the crashes, if so, then im not too sure... perhaps a problem with the disc?

You mean reinstalling it on the xbox?

Yeah, I've had many glitches/crashes gone wrong until i did the re-installation process and at least 90% of the time it fixes them.
do you have the game installed onto the hard drive or are you just playing it through the disc alone? because that could also be the problem. I always install games onto my hard drive before i play them.

We've got the game installed on the xbox, yes. Would reinstalling the game, or the addon be best?

i find it to be usually the best solution to breaking out glitches and crashes personally i think so. However, if this does not help then I would probably assume that it has something to do with the disc, the xbox or if you're playing the game for a long period of time which tends to give it a higher chance to crash on you.

How much space do you have free on the harddrive Daeaye? Where are your save games stored, on the hard drive or elsewhere? Do you have autosaving on or off?

For such a serious problem you would probably be better of contacting technical support for your region, but there are a few here who are always willing to try, just not many technical experts.

G-staff recommendation: http://www.gamesas.com/topic/1408809-getting-freezes-in-my-fully-built-home/