Steps to reproduce:

0) create project P
1) set a compiler defined in module X (other than Java module) as the default
IDE compiler (Project | Settings | Java Sources | Default Compiler)
2) create a new project
3) unistall the module X
4) restart the IDE
5) open project P

Mon Jan 15 11:32:57 IST 2001java.lang.ClassNotFoundException:
org.netbeans.modules.kjava.KJavaCompilerType
java.lang.ClassNotFoundException: org.netbeans.modules.kjava.KJavaCompilerType
	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at
org.netbeans.core.ClassLoaderSupport.findClass(ClassLoaderSupport.java:82)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
	at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
	at java.lang.Class.forName0(Native Method)
	at java.lang.Class.forName(Class.java:195)
	at org.openide.ServiceType$Handle.getServiceType(ServiceType.java:239)
	at
org.netbeans.modules.java.settings.JavaSettings.getCompiler(JavaSettings.java:90
)
	at
org.netbeans.modules.web.core.ServletSettings.getCompiler(ServletSettings.java:8
5)
	at java.lang.reflect.Method.invoke(Native Method)
	at org.openide.options.SystemOption.writeExternal(SystemOption.java:117)
	at
org.openide.util.SharedClassObject$WriteReplace.writeObject(SharedClassObject.ja
va:370)
	at java.lang.reflect.Method.invoke(Native Method)
	at
java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1878)
	at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1210)
	at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366)
	at
org.netbeans.modules.projects.content.XMLSupport.encodeValue(XMLSupport.java:147
)
	at
org.netbeans.modules.projects.content.XMLSettingsSet.write(XMLSettingsSet.java:1
54)
	at
org.openidex.projects.ProjectSupport.projectSave(ProjectSupport.java:177)
	at org.netbeans.modules.projects.PSupport.projectSave(PSupport.java:268)
	at
org.netbeans.core.NbProjectOperation.storeLastProject(NbProjectOperation.java:62
)
	at org.netbeans.core.NbTopManager.exit(NbTopManager.java:587)
	at org.netbeans.core.NbTopManager.exit(NbTopManager.java:574)
	at
org.netbeans.core.actions.SystemExit.performAction(SystemExit.java:45)
	at org.netbeans.core.MainWindow$1.windowClosing(MainWindow.java:166)
	at
java.awt.AWTEventMulticaster.windowClosing(AWTEventMulticaster.java:291)
	at java.awt.Window.processWindowEvent(Window.java:798)
	at javax.swing.JFrame.processWindowEvent(JFrame.java:241)
	at java.awt.Window.processEvent(Window.java:774)
	at java.awt.Component.dispatchEventImpl(Component.java:2595)
	at java.awt.Container.dispatchEventImpl(Container.java:1213)
	at java.awt.Window.dispatchEventImpl(Window.java:912)
	at java.awt.Component.dispatchEvent(Component.java:2499)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:319)
	at
java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:103)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:84)