We were indeed able to reproduce the problem on IE.
It seems that IE doesn't use the first option of a select as default value if none is selected like all the other browsers do.
Could you try to edit the file administrator/components/com_hikashop/classes/field.php and replace the code:
		}else{
			$arg = 'size="1"';
		}by
}else{
			$arg = 'size="1"';
			if(is_string($value)&& empty($value) && !empty($field->field_value)){
				$found = false;
				$first = false;
				foreach($field->field_value as $oneValue => $title){
					if($first===false){
						$first=$oneValue;
					}
					if($oneValue==$value){
						$found = true;
						break;
					}
				}
				//set default value for IE
				if(!$found){
					$value = $first;
				}
			}
		}That should set a default value on the server side and avoid the problem on IE.