As an update. No longer think its the script template. My reason is I can open a VB Script task and same thing happens so both templates would need to be corrupted. So I went for applying Update 3
Started with
Microsoft Visual Studio Professional 2015
Version 14.0.23107.0 D14REL
Microsoft .NET Framework
Version 4.6.01055
Now on
Microsoft Visual Studio Professional 2015
Version 14.0.25431.01 Update 3
Microsoft .NET Framework
Version 4.6.01055
So update 3 appears to have fixed this issue.
Many Thanks
M