When I searched the .dll for you this is the info i Got "hmcencx.dll has been reported as a dangerous file and part of a virus, adware or spyware. source:http://www.dll4free.com/hmcencx.dll.html
Try to get a Good virus scanner or get rid of windows and join the world of GNU/Linux.
try to use kaspersky internet security (kis). but i warn u that if the virus is attached with system files then there is a possibility of crashing the os. else u can format ur system and use kis for scanning. make sure kis is up to date
get a good anti virus software like kis11 and scan your machine for viruses. once that is done u can either insert the windows cd and search for the dll file with the name hmcencx.dll or u could search for the file online download it. Then save the file to C:\User\user\AppData\Roaming\hmcencx.dll