File Picker window not displayed properly in Chrome

When you open the file picker window and click the add file button, the contents of the new pop-up window are offset to the bottom left hand side and partially hidden. As a result you cannot select any of options on the left hand side.

We're using the latest version of Chrome on Windows 8 (31.0.165.0.63) and Moodle 2.6+ (from 13/12/13). We're running Aardvark Post-IT theme but problem also occurs in Clean Theme (though slightly differently - picker contents are displayed underneath the filepicker window.)

Site is hosted at Arvixe running on Linux. Sql5.5 and php 5.3.27.

It worked fine on IE10. I can provide images of both problems if needed.