Help with iView Napper error message

[pahiti]

Hoping that someone can help me.
I've been using iView Napper for afew weeks now (working perfectly, I love it) but for some reason last night when I went to run it, it brought up an error message:-

iViewNapper 2010301
Unhandled exception has occured in your application. If you click Continue, the application will ignore this error and attempt to continue. If you click quite the application will close immediately.
Value cannot be null
Parameter name: input

I have pulled down the latest versions of both the iViewNapper_20130301 file and the rtmpdump-win32-2.3r557 files but this has made no difference, the error still happens and the app won't launch.
I'm running Windows 7 Home premium.

Any help would be gratefully received.

Thx
Pahiti