Hello Jose,
I haven't ran into that issue and I'm not sure about its cause and solution, but here are some ideas on what you could try/check (they are separate ideas, not a sequence of steps):
-Login as administrator to install the software
-Make sure your PC has enough memory and free space on the HD
-Copy the content of the CD to the HD, and run the installer from there
-Modern installers have setup.exe and setup.msi launchers, try to execute the .msi instead of the .exe
-Reinstall LabVIEW 6.1 and then DSC (before that, make a backup of any custom vi's/files that may be overwritten/removed, and then uninstall LabVIEW from Control Panel->Add/Remove Programs ..Agregar y quitar programas))
If none of these helps, let me know.
Regards,
JorgeM.