SilentPrint may fail to print PDF files when it is running as a Windows service but prints them without any problems when running normally (i.e. not as a service).
The problem can be encountered when the service logon account has been changed from the account assigned by SilentPrint when the service was installed.
To rectify the problem, perform the following...
1. Stop the SilentPrint service;
2. Go to c:\documents and settings\all users\application data\silentprint and open the SilentPrint.ini file.
3. Under the section titled [MISC], the Show Adobe Apps parameter value should be changed to Yes;
Show Adobe Apps=Y
4. Save and close SilentPrint.ini;
5. Start the SilentPrint service.