Debug/Run in Xcode stopped working. Executable settings are wrong and can't be fixed too

I've just had a strange problem show up with my XCode project. The project is one that I've been working on for 4+ years. Just today, when try to start debugging, the debugging view opens and the console says "[Session started at 2010-10-03 14:04:35 -0600.]" but nothin开发者_运维问答g else happens.

It seems that the executable is screwed up. If I open up the executable's (I've only got one in the project) settings window, in the General tab, the drop down for "Use whatever for standard input/output" says "No Value" and there are no other options in the menu. On the debugging tab I see "When using whatever" but the drop down menu for that is completely empty, and again the drop down for "Use whatever for standard input/output" says "No Value" with no other options. Also interestingly, the "Start executable after starting debugger" option is unchecked. However, checking it doesn't stick. If you close the Executable Info window, then reopen it, the setting has reverted to off.

I've tried creating a new executable, but the same thing happens. Closing the project/reopening it and restarting Xcode also have no effect.

I noticed that someone with the same problem posted on the Xcode mailing list, but they got no real answer: http://www.cocoabuilder.com/archive/xcode/263804-debug-run-executable-does-nothing.html?q=%22no+value%22+standard+input#263804 .

Any ideas?

Have you installed anything lately? Do newly-created projects misbehave in the same way? Do you have backups (or version control) and, if so, does restoring the project to a former state also behave the same way? If yes to any, you might try reinstalling Xcode Tools.