Css background-image hanging IE8 Sophos Web content scanner

Hi,

We are developing a web applciation in ASP.Net which uses master pages, themes and stylesheets. Several of the page elements include a background image set through the stylesheet (within a theme).

When running in IE8 on our local machines, we notice that some of these background images are stuck trying to download. This seems to happen regularly but randomly in that it could be when a button is pressed on the screen, when a new page is navigated to or the Browser Back button is pressed.

The images in question are jpgs between 31kb and 1kb each with an example from the stylesheet below:

#templatemo_banner

{ width: 890px; height: 110px; padding: 50px 50px; background: url("images/templatemo_banner_bg.jpg") no-repeat center top; }

The website works perfectly in Firefox and Chrome and also in IE when we disable the Sophos web content scanner so our question is what could be causing this to happen in IE and what could we do on our side to prevent this happening?

Thanks