IE suddenly locks up on site load

I’ve been using a theme called Chameleon from Elegant Themes. The site has be live for quite a long time. All of a sudden, my client has received some phone calls from client that claim their computer (PCs) locks when visiting his site and they must use Task Manager to shut down the browser. They all seem to be using IE7 – IE9. Nothing has changed so I don’t know why this is happening. I’m not able to duplicate the issue on my computers. I updated all plugins and to WP 3.5.1 but still no change.

I’ve scanned for malware…none. I’ve checked the site with a service called Litmus and it loads and looks fine across all systems/browsers…even on mobile devices.

Any thoughts on where to look…thanks in advance