I had this problem:

http://www.vbforums.com/showthread.php?t=659620

I delete Settings1.designer.vb from Visual Basic and now Visual Basic gave me this problem:

What should I do ? :|

Code:
Warning	1	A custom tool 'SettingsSingleFileGenerator' is associated with file 'My Project\Settings.settings', but the output of the custom tool was not found in the project.  You may try re-running the custom tool by right-clicking on the file in the Solution Explorer and choosing Run Custom Tool.
UPDATE:

If I choose Run Custom Tool, old problem reappears and i have agand 2 Settings (Settings / Settings1).