Groupbox border issue

I have a vb app and i recently noticed a strange problem with Groupboxes on one of the forms

The problem is, i can see through the borders of groupboxes, so let's say i opened the generated executable and place it over my desktop with nothing behind, i can clearly see parts of the wallpaper i have (check the image below)

enter image description here

Now the funny thing, i have not modified any of the properties of those groupboxes and i believe the problem started after i added the following to my app.config

 <startup useLegacyV2RuntimeActivationPolicy="true">
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
  </startup>

I added that part in order to be able to compile code using SQLite..

Any ideas how to fix this?

Solution

The only way I was able to duplicate what you are showing, is by setting the Forms AllowTransparency property to True and having the TransparencyKey set to ControlLightLight. You may want to double check for something similar in your program.