Win32:Malware-gen virus infection

How does one get rid of the Win32:Malware-gen computer virus infection, one that Avast has managed to take care of a few times?

First, I’m an Avast user and not an Avast Team member.

With a lack of detail it is almost impossible to make a suggestion.
How was it detected ?
A screenshot of the Avast Alert with the more details option might help.

The malware-gen name is a generic detection, so could encompass many different malware types under a generic method of detection.