Why am I getting this thing popping up in my window?

Probably related to the hardware you're running on. What OS, video card, driver version, etc.?

Cheers,

J.C.

The only thing I know is I am running on Vista (I'm a newbie)

Looks like your video card is screwing up the drawing of the floating gnomon in the bottom left corner. You can try turning that off in the display options (hit ‘d’ with the mouse in the viewport to bring up the dialog).

What kind of machine are you working on? Is it a laptop or a stationary one?
It looks like a problem with OpenGL, and Houdini uses that extensively.

If you right click on the “Computer” icon in the Vista start menu and choose “Properties”, some useful information will be presented. Look at my attached screenshots, and write a reply with the items I've underlined in the screenshots.

To get to the device manager, just click the Device manager link in the same window, to the upper left.

thanks andrej that was the problem

Well, I would say, that was the symptom, not the problem. Removing symptoms is not the same as removing problems… ;-)
Kinda like taking painkillers to “remove” pain. It helps there and then, but did it take away the source of the problem? No.