I just got done merging two Windows Mobile applications into one and a user complained that the combined version was missing a feature of one of the original apps. As I set out to prove him wrong I bumped into something very wierd. I set a breakpoint in the event in the old app that I was expecting to check and nothing happened. The form in the app did absolutely nothing. However, I was pushing all http traffic from the mobile device thru fiddler and I could see that the form was hitting the webservice that the new combined app was supposed to be using. The device also gave the beep code I had programmed in after a successful operation. I put a breakpoint in a couple of other methods like Form.Load and Form.Close and even a couple of Button.Click events and those I was able to debug. I wasn't loading any assemblies in the GAC but even if I was I couldn't explain this partial debugging ability. The new app was on the device but it was in a separate folder so at first I disregarding the possibility that I was getting some sort of cross contamination. But then I thought what if the other app is actually running? Sure enough, after checking task manager, I could see the new app was running in the background and killing it let me debug the old app. How did this happen? The classes do have the same namespace and name but I've never heard of an app sharing another app's code in memory.