Hi,
See if you can uninstall your current version of HP Support Assistant by using the Microsoft 'Fixit' on the following link - this is particularly useful in correcting issues on machines running a 64bit OS.
http://support.microsoft.com/mats/Program_Install_and_Uninstall
If this is successful, restart the PC before installing the latest version of HP Support Assistant - see the link below for the latest download.
http://h18021.www1.hp.com/helpandsupport/hp-support-assistant.html
Regards,
DP-K