First, I'd like you to remove Virtual Dub. Use Revo Uninstaller in my sig. Choose the advanced removal option when asked. Make sure you remove any registry entries & files left over. Reboot the machine when finished.
Now, I'm no expert on this particular subject. However, based on the research I've done CamStudio might be an alternative. Its also free and includes some extra codecs.
Let me know how it works.
Edited by Ectech, 09 June 2009 - 04:14 PM.