Ok, then head over to this link
http://www.modthesims.info/wiki.php?title=Game_Help:Installing_Sims_3_Package_Files.

And download the Resource.cfg & d3dx9_31.dll files, there are instructions as to where they go, and then try it again, that should solve the problem.

I don't think it's possible to do without mods, but you can do it with the NRaas super computer found here.
http://ts3.tscexchange.com/index.php?PHPSESSID=3194b94ba7e492a8562d46f5ac8e14bc&topic=996.0

Just create you family the way you want them, set the teen as the child of the adult, and lave the young adult alone for now.  After you have moved them in, click the parent sim, you should get a "Master Control" option.  Under that menu there will be a few options and some more sub menus, click the "Advanced" menu, which will give you the option to change your family tree.

After you're inside the Advanced sub menu, click "Add Child", This will bring up the last menu you'll need to work with, it will list all of the town's sims filed into different categories, click either Gender:Male or Gender:Female, depending on the sex of the young adult, this will display all the ladies/gentlemen alphabetically by their last names, should be easy enough to find then, after you've done all of that.  Check your family tree, it should have him or her in the branches now.

Sorry for the semi-rant/explanation, but I hope that explains everything, Good luck

I'm sure you had seen something along the lines I'm about to give somewhere but...

Have you tried looking through your custom items for any clashing mods?  If you had recently patched or installed WA, some of your mods may be incompatible and cause glitching.

No Problem

Not sure if this is exactly what you're looking for, but I found some over a MTS2

http://www.modthesims.info/download.php?t=37797

Won't help before they steal your dinner, but here's a site that has some items that will help you get revenge, http://www.simwardrobe.com/

Most are lasers and pistols, but I prefer the crate of throwing axes myself.

Anyway, after you download (Insert random item of death here), just enter the lot in construction mode and set the item on the lot.

And thanks to Paladin for the awesome objects on his site