I installed Netbeans 7.4 yesterday and have all my codes migrated from NB7.3.1 to 7.4.

I can complie all codes, but I can not run any FXML projects. I go the 
following errors:
Executing C:\JavaWS\PaxSysProjGroup\JavaFXApplication8\dist\run678766717\JavaFXApplication8.jar using platform C:\Program Files\Java\jdk1.7.0_21\jre/bin/java
Exception in Application constructor
java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at com.javafx.main.Main.launchApp(Main.java:642)
	at com.javafx.main.Main.main(Main.java:805)
Caused by: java.lang.RuntimeException: Unable to construct Application instance: class javafxapplication8.JavaFXApplication8
	at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:393)
	at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:47)
	at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:115)
	at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
	at javafxapplication8.JavaFXApplication8.<clinit>(JavaFXApplication8.java:24)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
	at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:276)
	... 3 more
Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
	at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
	... 9 more

Tried to add a new FXML project to the project group. I can compile and run it if I have not added a reference to slf4j and logback. Once I added a reference to slf4j and logback and added codes to my main class

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
 
public class JavaFXApplication8 extends Application
{
	private static final Logger LOG = LoggerFactory.getLogger(JavaFXApplication8.class);
...

The project can be compiled successfully, but I will get the same error aformentioned when I run the project.

BTW, I don't get any issue like that with NB7.3.1