Class Not Found Issue in Eclipse

Recently I have come across a really strange bug in Eclipse 3.4.2 version. After adding new java class Eclipse refused to find it. And suddenly, it marked all my custom class imports as not found. Cleaning project, restarting IDE would not help. If you experience the same problem there is a simple quick solution. All you need is to change “Default output folder” in Project Properties/Java Build Path. Once you change output folder all those “class not found” errors will go away. Strange enough, but now you can change output folder path to the previous value and it will still compile correctly.

I am not sure what is the real cause of this error,  one possibility is that maven plug-in somehow interferes with the process. If it is Eclipse itself then upgrade to 3.5 version may resolve this issue. Need to check.