tried to run and recd this error

java.lang.NullPointerException
at edu.rice.cs.drjava.ui.MainFrame$ModelListener.interactionEnded(MainFrame.java:7453)
at edu.rice.cs.drjava.model.GlobalEventNotifier.interactionEnded(GlobalEventNotifier.java:331)
at edu.rice.cs.drjava.model.repl.InteractionsEventNotifier.interactionEnded(InteractionsEventNotifier.java:75)
at edu.rice.cs.drjava.model.repl.DefaultInteractionsModel$3.run(DefaultInteractionsModel.java:136)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

System Properties:
DrJava Version 20080112-0033
drjava.debug.port = 49472
java.runtime.name = Java(TM) SE Runtime Environment
sun.boot.library.path = C:\Program Files\Java\jre1.6.0_07\bin
java.vm.version = 10.0-b23
java.vm.vendor = Sun Microsystems Inc.
java.vendor.url = http://java.sun.com/
path.separator = ;
java.vm.name = Java HotSpot(TM) Client VM
file.encoding.pkg = sun.io
user.country = US
sun.os.patch.level =
java.vm.specification.name = Java Virtual Machine Specification
user.dir = <anonymized user.home>\Desktop\DrJava
java.runtime.version = 1.6.0_07-b06
java.awt.graphicsenv = sun.awt.Win32GraphicsEnvironment
java.endorsed.dirs = C:\Program Files\Java\jre1.6.0_07\lib\endorsed
os.arch = x86
java.io.tmpdir = <anonymized user.home>\AppData\Local\Temp\ line.separator = "\u000d\u000a"
java.vm.specification.vendor = Sun Microsystems Inc.
user.variant =
os.name = Windows Vista
application.home = <anonymized user.home>\Desktop\DrJava
sun.jnu.encoding = Cp1252
java.library.path = <anonymized user.home>\Desktop\DrJava;.;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Program Files\ATI Technologies\ATI.ACE;C:\Program Files\Common Files\Roxio Shared\DLLShared\;C:\Program Files\Common Files\Roxio Shared\DLLShared\;C:\Program Files\Common Files\Roxio Shared\9.0\DLLShared\;C:\Program Files\QuickTime\QTSystem\ env.class.path = .;.;C:\PROGRA~1\JMF21~1.1E\lib\sound.jar;C:\PROGRA~1\JMF21~1.1E\lib\jmf.jar;C:\PROGRA~1\JMF21~1.1E\lib;
java.specification.name = Java Platform API Specification
java.class.version = 50.0
sun.management.compiler = HotSpot Client Compiler
os.version = 6.0
user.home = <anonymized user.home>
user.timezone = America/New_York
java.awt.printerjob = sun.awt.windows.WPrinterJob
file.encoding = Cp1252
java.specification.version = 1.6
java.class.path = <anonymized user.home>\Desktop\DrJava\drjava-stable-20080106-0744.exe
user.name = <anonymized user.name>
java.vm.specification.version = 1.0
java.home = C:\Program Files\Java\jre1.6.0_07
sun.arch.data.model = 32
user.language = en
java.specification.vendor = Sun Microsystems Inc.
awt.toolkit = sun.awt.windows.WToolkit
java.vm.info = mixed mode, sharing
java.version = 1.6.0_07
java.ext.dirs = C:\Program Files\Java\jre1.6.0_07\lib\ext;C:\Windows\Sun\Java\lib\ext
sun.boot.class.path = C:\Program Files\Java\jre1.6.0_07\lib\resources.jar;C:\Program Files\Java\jre1.6.0_07\lib\rt.jar;C:\Program Files\Java\jre1.6.0_07\lib\sunrsasign.jar;C:\Program Files\Java\jre1.6.0_07\lib\jsse.jar;C:\Program Files\Java\jre1.6.0_07\lib\jce.jar;C:\Program Files\Java\jre1.6.0_07\lib\charsets.jar;C:\Program Files\Java\jre1.6.0_07\classes
java.vendor = Sun Microsystems Inc.
file.separator = \ java.vendor.url.bug = http://java.sun.com/cgi-bin/bugreport.cgi
sun.io.unicode.encoding = UnicodeLittle
sun.cpu.endian = little
java.rmi.server.hostname = 127.0.0.1
sun.desktop = windows
sun.awt.exception.handler = edu.rice.cs.drjava.ui.DrJavaErrorHandler
sun.cpu.isalist =

#DrJava configuration file
#Wed Sep 24 21:03:14 EDT 2008
extra.classpath = C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\javazoom.jar;C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\jmf.jar;C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\sound.jar;C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses
font.main = Monospaced-24
font.line.numbers = Monospaced-14
lineenum.enabled = true
key.delete.next = shift DELETE
key.delete.previous = shift BACK_SPACE
interactions.reset.prompt = false
save.before.compile = true
recent.files = [C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\MovieMaker3.java,C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\MovieMaker (2).java,C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\MovieMaker.java,C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\MovieCapturePanel.java,C:\\Users\\&lt;anonymized user.name>\\Desktop\\Alice and Media Comp\\intro-prog-java\\bookClasses\\MovieCapturer.java]
window.height = 776
window.width = 1176
window.x = 56
window.y = 39
last.dir = C:\\Users\\&lt;anonymized user.name>\\Desktop\\MediaComp\\intro-prog-java\\bookClasses\\AnimationPanel.java
last.interactions.dir = C:\\Users\\&lt;anonymized user.name>\\Desktop\\MediaComp\\intro-prog-java\\bookClasses

Used memory: about 23.30 megabytes
Free memory: about 2.71 megabytes
Total memory: about 26.02 megabytes
Total memory can expand to: about 63.56 megabytes