Not sure how much sense that title makes, but the issue that I am running into is that when I begin debugging a project (XYZ) a page from a completely different project (ABC), that is in a different solution will pop up when it hits an exception.
These are two totally different projects that contain custom code that is being run against the same SharePoint instance. I took a screen shot of what is going on:

The tab that is selected has popped up and thrown a null reference exception, but if you look in my solution explorer you will see that this file does not exist there. Why would something like this happen?