The URL looks odd, the spaces should be %20 since its a web URL, also, you might not have the required class setup to create the URL. The Ventrilo installer last I looked does not add the keys correctly.
Here is a Reg file to re-add it IF everything was installed to the default directory.
PHP Code:
Windows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Ventrilo]
"URL Protocol"=""
@="URL:Ventrilo Protocol"
[HKEY_CLASSES_ROOT\Ventrilo\DefaultIcon]
@="C:\\Program Files\\Ventrilo\\Ventrilo.exe,1"
[HKEY_CLASSES_ROOT\Ventrilo\shell]
[HKEY_CLASSES_ROOT\Ventrilo\shell\open]
[HKEY_CLASSES_ROOT\Ventrilo\shell\open\command]
@="C:\\\\PROGRA~1\\\\Ventrilo\\\\Ventrilo.exe -l%1"
You want to save that file with a .reg extension and you should be good to go.