Why do I keep getting this pop-up?

Avast Free Antivirus / Premium Security
1

I’m using the free version of Avast.

At random times, I get the following pop-up:

http://i40.tinypic.com/femgwo.jpg

It disappears in about 1 sec but I have no idea why I’m getting this popup at random times. I am using a MS outlook sidebar widget that tells me my upcoming appointments. It’s called Outlook Appointments. Maybe that’s the cause?
In any case, I do NOT want to see this pop-up. How do I make it disappear?

2

When avast finds Outlook installed, the Mail Shield uses a special plug-in which works with your Outlook email rather than using the default Mail Shield function. This is a splash screen to let you know it is loading.

You can change that in the Mail Shield, Expert Settings, Behaviour, uncheck the ‘Show splash screen’ option.