I am getting this error.
Locating source for \'C:\\Users\\cem\\Documents\\Visual Studio 2008\\Projects\\CS.Web.Controls\\WebCropImage\\CropImage.cs\'. Checks
Open "Solution 'YourSolutionName' property pages" window (go to main menu: Project->Properties) and then go to "Debug Source Files". Check under "Do not look for these source files" window if you have your problematic file path written in it. If yes, delete the path and try again. I think this might solve your problem.
Regards,