Product Version: NetBeans IDE 7.3 (Build 201302132200)
Java: 1.7.0_13; Java HotSpot(TM) 64-Bit Server VM 23.7-b01
Runtime: Java(TM) SE Runtime Environment 1.7.0_13-b20
System: Windows 7 version 6.1 running on amd64; Cp1252; en_US (nb)
User directory: C:\Users\quaglan\AppData\Roaming\NetBeans\7.3
Cache directory: C:\Users\quaglan\AppData\Local\NetBeans\Cache\7.3

Everytime I start up NetBeans, after a short while, the striped red disk icon appears on the right of the status bar signalling an exception.
If I clock on it a dialog opens and shows the following trace:

java.lang.ArrayIndexOutOfBoundsException
	at java.lang.System.arraycopy(Native Method)
	at java.io.PushbackInputStream.unread(PushbackInputStream.java:235)
	at org.netbeans.modules.uihandler.Installer.copyWithEncoding(Installer.java:1458)
	at org.netbeans.modules.uihandler.Installer$Submit.doShow(Installer.java:1634)
	at org.netbeans.modules.uihandler.Installer.displaySummary(Installer.java:1001)
	at org.netbeans.modules.uihandler.Installer.access$400(Installer.java:114)
	at org.netbeans.modules.uihandler.Installer$2Auto.run(Installer.java:576)
	at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1432)
[catch] at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2044)

Then, if I click on "Review and Report Problem", the dialog box disappears and nothing happens.

NetBeans continues to work normally after that.