Hi,
Hcm.exe is a program, which is to say, it will install itself into your computer.
It is not harmful, but it's something you don't really need.....it can be used as a task manager for rarely used programs.
Tell your Norton security to not allow it.
You can go to
http://www.google.com, type in the name you want info on, then click on Search, to read many, many links associated with that name.
As a general rule, I would not allow any .exe file to be downloaded from the web, UNLESS it's a download that you are doing yourself.....such as downloading an install file from some site.
You will be spending a lot of time at first, telling these pop-ups whether to allow them or not.
You can accomplish the same thing by using a great, free program called Spyware Blaster. This program, when installed, automatically stops stuff like this from being downloaded, without asking you. It is not a scanner, (you don't have to scan with it like AdAware, etc), but can be updated regularly, just like Anti-virus definitions.
If interested, you can get it at:
http://www.javacoolsoftware.com/sbdownload.html
It's called Spyware Blaster 3.3
Best wishes,
fredg