I'll attach the system/ portion of my userdir in case it yields some insight
in what the problem can was. I noticed that workspace.ser_hidden is
empty - perhaps that's relevant:

rw-r--r--   1 tor      staff           0 Oct 19 10:46 workspace.ser_hidden


-- System Info ----------------------------------------------------------------
  Product Version       = NetBeans IDE, Development Version (Build 200110190909)
  IDE Versioning        = IDE/1 spec=1.41 impl=200110190909
  Operating System      = SunOS version 5.8 running on sparc
  Java; VM; Vendor      = 1.3.1_01; Java HotSpot(TM) Client VM 1.3.1_01; Sun
Microsystems Inc.
  Java Home             = /home/tor/ifdef/jvm/j2sdk1_3_1_01/jre
  System Locale         = en_US
  Home Dir; Current Dir = /home/tor; /home/tor/ws/demo_ws
  IDE Install; User Dir = /home/tor/ifdef/ide/cvs/nbbuild/netbeans;
/home/tor/nbuser30
  CLASSPATH             =
 /home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/patches/openide-compat.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/core.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/openide.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/crimson.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/jh.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/regexp.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/rmi-ext.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/servlet.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/terminalemulator.jar:/home/tor/ifdef/ide/cvs/nbbuild/netbeans/lib/ext/xerces.jar:/set/workshop/rufous/ifdef/jvm/current/lib/dt.jar:/set/workshop/rufous/ifdef/jvm/current/lib/htmlconverter.jar:/set/workshop/rufous/ifdef/jvm/current/lib/tools.jar
-------------------------------------------------------------------------------
Existing modules:
        Ant [org.apache.tools.ant.module/2 2.6 200110171039]
        Applet [org.netbeans.modules.applet/1 1.7 200110171039]
        Auto Update [org.netbeans.modules.autoupdate/1 1.7 200110171039]
        Bean Patterns [org.netbeans.modules.beans/1 1.7 200110171039]
        Built-in CVS Client [org.netbeans.modules.cvsclient/1 1.4 200110171039]
        C, C++ and Fortran Editor Support [org.netbeans.modules.cpp.editor/1 1.0
200110081500]
        C, C++ and Fortran Support [org.netbeans.modules.cpp/1 1.0 200110081500]
        CVS Command-Line Client Support Converter
[org.netbeans.modules.vcs.cmdline.compat/1 1.0
 200110171051]
        Editor [org.netbeans.modules.editor/1 1.8 200110171039]
        Editor Chooser [org.netbeans.modules.externaleditor.editorchooser/1 1.0
200110010933]
        External Editor Support [org.netbeans.modules.externaleditor 0.5
200110081501]
        External HTML Browser [org.netbeans.modules.extbrowser/1 0.3 200110171039]
        Form Editor [org.netbeans.modules.form/2 1.7 200110171039]
        Forte Developer C/C++/Fortran Support [com.sun.forte.developer.ipe/1 0.5
Forte Developer 7
 C/C++/Fortran Support 1.0 Dev 2001/10/19]
        General Online Help [org.netbeans.modules.usersguide/1 1.8 200110171051]
        HTML [org.netbeans.modules.html/1 1.8 200110171039]
        HTTP Server [org.netbeans.modules.httpserver/1 1.7 200110171039]
        IDE Core [org.netbeans.core/1 1.1]
        Image [org.netbeans.modules.image/1 1.7 200110171039]
        Internationalization [org.netbeans.modules.i18n/1 1.9 200110171039]
        Internationalization of Form [org.netbeans.modules.i18n.form/2 1.8
200110171039]
        JAR Packager [org.netbeans.modules.jarpackager/2 1.9 200110171039]
        JNDI [org.netbeans.modules.jndi/1 1.4 200110171039]
        JPDA Debugger [org.netbeans.modules.debugger.jpda/1 1.9 200110171039]
        JSP Syntax Coloring [org.netbeans.modules.web.core.syntax/1 1.5
200110171039]
        JSP/Servlet [org.netbeans.modules.web.core/1 1.5 200110171039]
        Java Source Files [org.netbeans.modules.java/1 1.7 200110171039]
        Javadoc [org.netbeans.modules.javadoc/1 1.7 200110171039]
        New Module Wizard [org.netbeans.modules.apisupport.lite/1 0.2 200110171039]
        Projects [org.netbeans.modules.projects/1 1.7 200110171039]
        RMI [org.netbeans.modules.rmi/1 1.4 200110171039]
        Resource Bundle Syntax Coloring
[org.netbeans.modules.properties.syntax/1 1.7 200110171039]
        Resource Bundles [org.netbeans.modules.properties/1 1.7 200110171039]
        Scripting Support [org.netbeans.modules.scripting/1 1.4 200110171039]
        Sourceless Java Classes [org.netbeans.modules.clazz/1 1.8 200110171039]
        Text [org.netbeans.modules.text/1 1.7 200110171039]
        Tomcat 3.2 Server [org.netbeans.modules.web.tomcat/1 1.3 200110171051]
        Tools Debugger [org.netbeans.modules.debugger.debug/1 1.9 200110171039]
        User Utilities [org.netbeans.modules.utilities/1 1.7 200110171051]
        VCS Generic Command-Line Support [org.netbeans.modules.vcs.advanced/1
1.5 200110171051]
java.lang.NullPointerException
        at
 org.netbeans.core.windows.layers.WorkspaceData$InstanceCookieImpl.orderModes(WorkspaceData.java:471)
        at
 org.netbeans.core.windows.layers.WorkspaceData$InstanceCookieImpl.createModes(WorkspaceData.java:439)
        at
 org.netbeans.core.windows.layers.WorkspaceData$InstanceCookieImpl.updateModes(WorkspaceData.java:345)
        at
 org.netbeans.core.windows.layers.WorkspaceData$InstanceCookieImpl.updateAll(WorkspaceData.java:269)
        at
 org.netbeans.core.windows.layers.WorkspaceData$InstanceCookieImpl.loadDataSection(WorkspaceData.java:627)
        at
org.netbeans.core.windows.WorkspaceImpl.ensureSectionLoaded(WorkspaceImpl.java:895)
        at
org.netbeans.core.windows.WorkspaceImpl.getDisplayName(WorkspaceImpl.java:223)
        at
org.netbeans.core.windows.WorkspaceSwitcher.addNew(WorkspaceSwitcher.java:251)
        at
org.netbeans.core.windows.WorkspaceSwitcher.<init>(WorkspaceSwitcher.java:83)
        at org.netbeans.core.windows.MainWindow.showWindow(MainWindow.java:191)
        at org.netbeans.core.Main.initializeMainWindow(Main.java:270)
        at org.netbeans.core.NonGui.run(NonGui.java:571)
        at org.netbeans.core.Main.run(Main.java:216)
        at org.openide.TopManager.initializeTopManager(TopManager.java:120)
        at org.openide.TopManager.getDefault(TopManager.java:81)
        at org.netbeans.core.Main.main(Main.java:325)
        at org.netbeans.core.TopThreadGroup.run(TopThreadGroup.java:90)
        at java.lang.Thread.run(Thread.java:484)