ShellExecute failed, Error code 255

Description:    You are trying to install memoQ on a PC, and the install stops with the error message: ShellExecute failed, (Error Code: 255)

How to:    This is caused by the Avast antivirus, and can be solved by turning off Avast for the time of install.

Please note that creating an exception for the program in Avast does not solve the install issue.