Downloads don´t work - update?

[sunzet]

Hey

I have Sims 3 and Sims 3 Pets..
I have been downloaded free stuff from different sights where people has made stuff to use.
But they don´t work. F.e - you can´t place objects on desks or counters. And when I place a chair into a desk or table it kind of places within the desk/table. Very annoying.
It has not always been like this, so I wonder if Sims has placed a bug for that within a autoupdate?
We have the games installed on both a mac and a pc. And the problems occured at the same time on both.
Is there a way to come around this problem?