Is there any security threat in Windows 7 desktop themes?

I'm an IT in a small company. On our office machine the lady that runs it, once in a while she really likes to change Windows 7 desktop themes. She downloads them from right-clicking on desktop -> Personalize -> "Get more themes online" that goes to this page:
Themes - Microsoft Windows

For her it's all just pretty pictures (i.e. she doesn't know much about computer security.)

My question though is how secure are those Windows 7 desktop themes? And is there a potential that they could cause ANY harm?

Hello dc2000 I use them on my computer all the time. No problems, they do not harm your system in anyway....

Appreciate it, guys!

AddRAM said:

Changes like that shouldn`t be allowed

Everyone`s computer has to have the same background, no changes, no exceptions

It's a small office. We have just 2 desktops in there.

Why wouldn't it if it's safe?

Layback Bear said:

As long as you get your desktop pictures from where you state and no other place.

If pictures are downloaded from other sites you can get infected.

Just from curiosity, how can pictures be infected?