I never had the whole painting vanish but i did at one time have issue with large custom ones i d/l'd losing the image on the canvas. I think it was due to the painting itself was detailed and large so my lot was just too much for the memory to handle so the game dumped excess textures. I'd end up with paintingless canvas's..lol..

Not sure why they'd vanish. Have you run any patches like a hack? I get some weird glitches due to one that seems to mess with some scripting.

You may get the bug fixed using the suggestion Ekozski had but you may also want to make sure you have the current and latest drivers for direct x. The fact the picture of the house is misaligned with it's miniwindow looks more like an overlay problem. This might be a problem with the graphics card in that it's only 64MG or it could still be just the system using it wrong. If you can't resolve it with Nvidia drivers check if you have the last revision of direct x (9.0c i think is mine and the last release). There is also the tiny chance the card is corrupting the data due to a overheat so keep in mind if you were hammering at a 3d game and then loading sims 2 and getting this.. that could(though usually it produces random glitches, not the same one over and over) do it.