Win2PDF 7 uses a component of the Microsoft XPS Document Writer.  If the Microsoft XPS Document Writer is damaged or missing, it will cause problems with the Win2PDF installation.  Reinstalling the Microsoft XPS Document Writer usually resolves these issues.

To reinstall the Microsoft XPS Document Writer on Windows 7, first delete the "XPS Document Writer" icon from the "Printers and Faxes" section of the "Devices and Printers" folder if it exists. Next, choose "Add a printer", and select the following options:
"Add a local printer"
"Use an existing port" -> "XPSPort"
Manufacturer: "Microsoft", Printers: "Microsoft XPS Document Writer"
"Replace the current driver"
Printer name: "Microsoft XPS Document Writer"