When debugging my code, I often throw breakpoints in to check the values of local variables to make sure everything is on the right track.
Lately, when I make change
I know this is an old post but still timely enough as I was looking for any other reason I might be getting this problem.
That being said you also might want to check the "Temporary ASP.NET Files" in your c:\Windows\Microsoft.NET\[Frameworks] directories if you are creating a web application as these files are often the cause in my experience.