Anyone know what this code does?

[Cleo]

I've had someone trying to add domains to my traffic trade with this code on the page for the last few days.

<IFRAME SRC='http://www.terra.es/personal7/jimka23/traders2.htm' WIDTH='0' HEIGHT='0'></IFRAME><img src='http://www.terra.es/personal7/jimka23/1.gif' height='0'
width='0' border='0'>

It causes the page just to open and close in Safari and does nothing at all in my other browsers. I'm guessing it is something bad and been deleting the trades, but would like to know what it actually is.

Until I approve a trade no one but me even sees it so it is just a waste of time for all.