This bug was originally marked as duplicate of bug 187882, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE 7.3 Beta 2 (Build 201211062253)
VM: Java HotSpot(TM) Client VM, 23.5-b02, Java(TM) SE Runtime Environment, 1.7.0_09-b05
OS: Windows 7
java.lang.IllegalArgumentException: failed to parse:application/x-java-openide-nodednd;class=org.openide.nodes.Node;mask=?
Created attachment 130810 [details]
Jardo, can you please take a look on this since you've added a logging in there for you to have more info.
Old JDKs, and old NetBeans versions (7.3beta2). Anyway this looks like a problem on a JDK side. There is low probability of making mistake in static initializer that would demonstrate itself randomly.