Probably Visual Studio is configured to show and debug the .NET sources:
Sometimes this is usefull.
To disable it, try selecting "Enable Just My Code" from Options dialog, Debugging, General section. It can be opened from Tools menu. Maybe also adjust other options that are mentioned in article.
You can also press the "Show Call Stack" link from your picture, and navigate to your code.
this isn't my code . this is .net datagridview code