I am using a Toshiba Satellite with Windows XP Media Center Edition SP2 and an HP Printer-Scanner-Copier model 1315v. Everything was fine until a week ago. Then when I tried to open the HP Director or HP Image Zone or HP Document Viewer I get the error message: "The program has encountered an unexpected error: Parameter cannot be null. Parameter name: serializationStream" At that point the HP application shuts down, although I can still print documents and copy, but I can't scan. I have talked with the HP support folks three times, uninstalled and reinstalled the HP software, and the problems persists. Recently the same error message appeared before I even tried to use the HP device. So I think that the problem is with the Windows software rather than the HP software. I have my Toshiba Recovery and Applications/Drivers DVD. What can I do to fix this problem?