Could not find the main class Files\Netbeans. Program will exit

Question

Previously everything was fine. I haven't run Netbeans 7.0.1 for two weeks. Now when I start Netbeans I got this error. I am having Netbeans 7.0.1 and Windows 7 64bit. I have to use Netbeans 7.0.1 and JDK 6 for running my project. I delete windows temporary files, Netbeans cache from C:\Users\username.netbeans\7.0\var directory. I have installed JDK 6 and 7. I have other projects that run fine in Netbeans 7.4 and JDK 7.

I was facing the same problem many times, and after some time after this error netbeans started, but now it doesn't.

I read that this problem usually happens if your PC runs out of memory and you force quit it Netbeans.

Could you help me? Here is an image

Here is the error I got in my console:

The launcher has determined that the parent process has a console an
it for its own console output.
Closing the console will result in termination of the running progra
Use '--console suppress' to suppress console output.
Use '--console new' to create a separate console window.
Exception in thread "main" java.lang.NoClassDefFoundError: Files\Net
Caused by: java.lang.ClassNotFoundException: Files\NetBeans
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

Could not find the main class: Files\NetBeans. Program will exit.