iPhone Simulator (IndigoDevice) Internal Error

I got a strange "Internal Error" when building app with Xcode. Restarting Xcode and my Mac do not help. Finally, I found the solution from JPoz:
http://blog.jpoz.net/2009/05/24/iPhone-simulator-internal-error.html
"go into your (username)/Library/Application Support/ and delete the iPhone Simulator folder. Restart xcode and build your app."
It works fine and help a lot.



=============== Error Message: ===================
"Internal Error
File: /SourceCache/IndigoDebuggingPlugin/IndigoDebuggingPlugin-31/IndigoDevice/XCiPhoneSimulatorDevice.m
Line: 265
Object:
Method: _launchSimulatedExecutable:

Assertion failed: nil == _currentSimulatorSession"