Update 10/17/11: Our testing has indicated that the latest update from AVG resolves this issue.  If you have the problem described below, please update your AVG software to eliminate this problem.

We have recently discovered that there is a conflict between MediaShout and AVG Internet Security 2012.  This issue affects both v3.x and v4.x.  The problem is with the Identity Protection module, and it shows up as a series of 'Invalid Argument' errors that you can never stop for more than a few seconds.  

To resolve this issue, please disable the Identity Protection module:

1. Open the AVG control panel;
2. Right-Click on the 'Identity Protection' module and select 'Show in Advanced settings...";
3. Select 'Identity Protection settings' and uncheck 'Activate Identity Protection', then click 'OK';
4. Exit AVG and then MediaShout should work correctly.

There is a feature allowing you to set an exclusion for software that you do not want that module to interfere with, but in our experience it did not stop the issue -- only disabling the module was effective.  (If you find a way to add an exclusion that works, please let us know.)

Here is a video demonstrating how to change the settings: