To force the driver to be unloaded, which may be the only way to remove a progress dialog which won't otherwise go away (or to install an update of the driver), the easiest approach is to use the Task Manager to kill the process pdfSaver5.exe (or pdfSaver3.exe for version 3). You can also do it via one of the following Start...Run... command lines:
Version 5:
"C:\Program Files\Tracker Software\PDF-XChange 5\pdfSaver5.exe" /quit
Version 3:
"C:\Program Files\Tracker Software\PDF-XChange 3\pdfSaver\pdfSaver3.exe" /quit
