This bug was originally marked as duplicate of bug 157335, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.
Build: NetBeans IDE Dev (Build nbms-and-javadoc-4950-on-100308)
VM: Java HotSpot(TM) Server VM, 16.0-b13, Java(TM) SE Runtime Environment, 1.6.0_18-b07
OS: Windows XP
mklaehn: navigating heapdump by keyboard
View: Fields in Instances View
pressing right arrow key in on node for java.util.HashMap -> this -> table -> ANY index that has value "null"
Created attachment 96506 [details]
Thanks for catching it! Easily reproducible according to the provided steps.
Fixed in profiler-main:
Integrated into 'main-golden', will be available in build *201005100200* on http://bits.netbeans.org/dev/nightly/ (upload may still be in progress)