This exception happens on Solaris, when I start IDE and set first breakpoint
in a project (modified Welcome project in my case). 

java.lang.ClassCastException:
org.netbeans.modules.cnd.debugger.gdb.breakpoints.BreakpointAnnotationListener
        at
org.netbeans.modules.cnd.debugger.gdb.actions.ToggleBreakpointActionProvider.getBreakpointAnnotationListener(ToggleBreakpointActionProvider.java:86)
        at
org.netbeans.modules.cnd.debugger.gdb.actions.ToggleBreakpointActionProvider.doAction(ToggleBreakpointActionProvider.java:70)
        at org.netbeans.spi.debugger.ActionsProvider$1.run(ActionsProvider.java:77)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:493)
[catch] at
org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:926)

If I press Ok, breakpoint sign does not appear on this line.
If I try to set this breakpoint again, the same exception happens.
There is no workaround. The only way is to exit IDE and start again.

Here is a part of code where exception happens (see line 86):
-------------------------------------------------------------
84:    private BreakpointAnnotationListener getBreakpointAnnotationListener() {
85:        if (breakpointAnnotationListener == null) {
86*            breakpointAnnotationListener = (BreakpointAnnotationListener) 
87:                DebuggerManager.getDebuggerManager().lookupFirst(null,
BreakpointAnnotationListener.class);
88:        }
89:        return breakpointAnnotationListener;
90:    }
-------------------------------------------------------------