I had 2 open projects in ide and deleted them one by one. After deleting the second IDE become frozen.

  Product Version         = NetBeans IDE Dev (Build 101011-6b6749d834ec) (#6b6749d834ec)
  Operating System        = Linux version 2.6.32-24-generic running on amd64
  Java; VM; Vendor        = 1.6.0_20; Java HotSpot(TM) 64-Bit Server VM 16.3-b01; Sun Microsystems Inc.
  Runtime                 = Java(TM) SE Runtime Environment 1.6.0_20-b02
  Java Home               = /usr/lib/jvm/java-6-sun-1.6.0.20/jre

Found one Java-level deadlock:
=============================
"Default RequestProcessor":
  waiting to lock monitor 0x00000000410437b8 (object 0x00007f84fed03670, a java.lang.Class),
  which is held by "Opening projects"
"Opening projects":
  waiting to lock monitor 0x00000000411cbd18 (object 0x00007f850a9bce50, a org.netbeans.modules.project.ui.OpenProjectList$RecentProjectList),
  which is held by "Default RequestProcessor"

Java stack information for the threads listed above:
===================================================
"Default RequestProcessor":
	at org.netbeans.modules.project.ui.OpenProjectList.getDefault(OpenProjectList.java:227)
	- waiting to lock <0x00007f84fed03670> (a java.lang.Class for org.netbeans.modules.project.ui.OpenProjectList)
	at org.netbeans.modules.project.ui.