In 
Product Version: NetBeans IDE Dev (Build 201108030600)
Java: 1.7.0; Java HotSpot(TM) Client VM 21.0-b17
System: Windows 7 version 6.1 running on x86; Cp1252; fr_FR (nb)


the UI freeze after a couple of minutes.
using VisualVM shows the following thread being blocked:
"HintsController worker" daemon prio=2 tid=0x0a6f3800 nid=0xe7c waiting for monitor entry [0x0c06f000]
   java.lang.Thread.State: BLOCKED (on object monitor)
	at java.awt.Container.invalidateTree(Container.java:1714)
	- waiting to lock <0x181a0a68> (a java.awt.Component$AWTTreeLock)
	at java.awt.Container.setFont(Container.java:1747)
	at javax.swing.JComponent.setFont(JComponent.java:2751)
	at org.openide.text.QuietEditorPane.setFont(QuietEditorPane.java:132)
	at org.netbeans.modules.editor.lib2.view.DocumentViewOp.updateDefaultFontAndColors(DocumentViewOp.java:809)
	at org.netbeans.modules.editor.lib2.view.DocumentViewOp.checkSettingsInfo(DocumentViewOp.java:685)
	at org.netbeans.modules.editor.lib2.view.DocumentViewOp.checkViewsInited(DocumentViewOp.java:503)
	at org.netbeans.modules.editor.lib2.view.DocumentView.modelToY(DocumentView.java:716)
	at org.netbeans.editor.BaseTextUI.getYFromPos(BaseTextUI.java:324)
	at org.netbeans.editor.GlyphGutter.changedLine(GlyphGutter.java:654)
	at org.netbeans.editor.Annotations.fireChangedLine(Annotations.java:644)
	at org.netbeans.editor.Annotations.refreshLine(Annotations.java:564)
	at org.netbeans.editor.Annotations.addAnnotation(Annotations.java:300)
	at org.netbeans.modules.editor.NbEditorDocument.addAnnotation(NbEditorDocument.java:233)
	at org.openide.text.NbDocument.addAnnotation(NbDocument.java:504)
	at org.netbeans.modules.editor.hints.ParseErrorAnnotation.attachAnnotation(ParseErrorAnnotation.java:149)
	- locked <0x2003ed40> (a org.netbeans.modules.editor.hints.ParseErrorAnnotation)
	at org.netbeans.modules.editor.hints.AnnotationHolder$NbDocumentAttacher.attachAnnotation(AnnotationHolder.java:240)
	at org.netbeans.modules.editor.hints.AnnotationHolder.attachAnnotation(AnnotationHolder.java:222)
	at org.netbeans.modules.editor.hints.AnnotationHolder.updateAnnotationOnLine(AnnotationHolder.java:692)
	at org.netbeans.modules.editor.hints.AnnotationHolder.setErrorDescriptionsImpl(AnnotationHolder.java:981)
	- locked <0x2003ed80> (a org.netbeans.modules.editor.hints.AnnotationHolder)
	at org.netbeans.modules.editor.hints.AnnotationHolder.access$1400(AnnotationHolder.java:120)
	at org.netbeans.modules.editor.hints.AnnotationHolder$5.run(AnnotationHolder.java:894)
	at org.netbeans.editor.BaseDocument.render(BaseDocument.java:1422)
	at org.netbeans.modules.editor.hints.AnnotationHolder.setErrorDescriptions(AnnotationHolder.java:891)
	at org.netbeans.modules.editor.hints.HintsControllerImpl.setErrorsImpl(HintsControllerImpl.java:111)
	at org.netbeans.modules.editor.hints.HintsControllerImpl.setErrors(HintsControllerImpl.java:93)
	at org.netbeans.spi.editor.hints.HintsController$1.run(HintsController.java:84)
	at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
	at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)

   Locked ownable synchronizers:
	- None