Page Focus / Scroll issue in Chrome- can only scroll background page - not colorbox window

In the Google Chrome browser on Windows 7 and 8.1 the mouse scroll wheel scrolls the background page rather than the colorbox window itself.

Both the colorbox window and and the background window have scrollbars - I can only scroll the background window however.

I've tried clicking in the colorbox window to change the focus but it doesn't change anything. I can only scroll the background page with the wheel.

I've tested it on two different machines with different operating systems. Also I get the same issue on three completely different hosting environments.

The scroll function works fine in Firefox and Internet Explorer - it seems to be a Chrome issue and is not confined to the individual browser settings on one machine.

You can see the issue by following any of the "View Sample" links on this page http://pelicandigital.com/portfolio

The problem windows were all created with the Colorbox Node plugin. Not sure if it a colorbox node issue or colorbox itself, so have posted on both issue pages.

I'd be really grateful for any help.

Thanks