Why wont NetBeans runt? (Malformed \uxxxx encoding error)

Question

I was working on a J2ME project and out of nowhere, I just started getting this error.
My syntax is correct everywhere and I haven't had problems running it before.

D:\Users\Ihato\NetBeansProjects\JavaMEGUI3\nbproject\build-impl.xml:6: 
java.lang.IllegalArgumentException: Malformed \uxxxx encoding.
    at java.util.Properties.loadConvert(Properties.java:568)
    at java.util.Properties.load0(Properties.java:390)
    at java.util.Properties.load(Properties.java:341)
    at org.apache.tools.ant.taskdefs.Property.loadProperties(Property.java:580)
    at org.apache.tools.ant.taskdefs.Property.loadFile(Property.java:597)
    at org.apache.tools.ant.taskdefs.Property.execute(Property.java:497)
    at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    at sun.reflect.GeneratedMethodAccessor178.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    at org.apache.tools.ant.Task.perform(Task.java:348)
    at org.apache.tools.ant.Target.execute(Target.java:390)
    at org.apache.tools.ant.Target.performTasks(Target.java:411)
    at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    at org.apache.tools.ant.module.bridge.impl.BridgeImpl.run(BridgeImpl.java:285)
    at org.apache.tools.ant.module.run.TargetExecutor.run(TargetExecutor.java:539)
    at org.netbeans.core.execution.RunClassThread.run(RunClassThread.java:153)
BUILD FAILED (total time: 0 seconds)

I have tried searching something about it but it's very poorly documented (5500 results on google)
Why is this happening?

First few lines of the XML are:

1 <?xml version="1.0" encoding="UTF-8"?>
2 <!-- *** GENERATED FROM project.xml - DO NOT EDIT *** -->
3 <project name="JavaMEGUI3-impl" default="jar" basedir="..">
4     <!--load-properties-->
5     <target name="pre-load-properties">
6         <property file="nbproject/private/private.properties"/>
7         <property name="user.properties.file" location="${netbeans.user}/build.properties"/>
8         <available property="user.properties.file.exists" file="${user.properties.file}"/>
9     </target>

I've checked the other projects and it's pretty much the same except for the name.