IE has a known bug where Internet Explorer file downloads over SSL do not work with the cache control headers.
You may be able to workaround this error by implementing the registry settings from this Microsoft KB Article. This script will help you implement it directly from your K1000 appliance. You will need to import it as a resource into your K1000 appliance (see documentation)
If this does not work then contact technical support who may be able to give you a patch workaround for it. .