Please, make sure the ultraslim dock firmware is up to date
(ver 2.30 sp75855 - http://h20566.www2.hp.com/hpsc/swd/public/detail?sp4ts.oid=7815295&swItemId=ob_165723_1&swEnvOid=4192 ),
then run HP Image Assistant to analyze that your system is up to date (drivers and firmware)
www.hp.com/go/clientmanagement
if Image Assistant does not support your 1040 G1, then use HP SDM - Softpaq Download Manager - available from the same site