Well I have some new information.
When using Windows Shell to attempt to print to a printer other than your default, there is a registry entry extremely similar to the one I mention in the first post.
"C:\Program Files (x86)\Adobe\Reader 11.0\Reader\AcroRd32.exe" /t “<Full path to PDF file.pdf>" "<network print queue name>" “winspool” “NE03:”
In the registry for shell using the printto verb - there is the following:
"C:\Program Files (x86)\Adobe\Reader 11.0\Reader\AcroRd32.exe" /t “%1" "%2" “%3” “%4”
where the specific parameter data is exactly the same as in the command line example.
Our customers were messing around trying to solve the printing problem on their own, and found that if you delete "%3" and "%4" from the registry entry, the attempt by our application to print the pdf from a shell was successful. It is only a short bit of logic to see that the two parameters being ignored are the print driver (winspool), and the port.
We read in other forums that the last two parameters are actually optional starting with Adobe X. We also know that when installing Adobe XI Reader, a proprietary printer driver is also installed. What we believe is happening is that when those last two parameters are missing, Adobe defaults to using their own local printer driver and/or spooler to print the pdf to the selected printer.
So that would indicate that something about using the Windows Print Spooler service is getting interfered with when Adobe Protected Mode is enabled.
So, while I haven't tried it yet, it means the following trust entries may be tried:
PROCESS_ALL_EXEC=%windir%\System32\spoolsv.exe
PROCESS_ALL_EXEC=%windir%\system32\svchost.exe
In addition the Services applet from the Control Panel can be used to verify the settings for the "Print Spooler" service, and the "RPC" service it depends on. These must have permissions set up correctly, and they must be running when the attempt to print is made.
Lastly, there may also be some other trust setting needed when using the Windows "Print Spooler" service.
While I get this next attempt tried at our customer, I am wondering if there is anyone that can confirm or deny anything that I am saying in this post? I could really use a comment from someone who is familiar with printing pdf's through Windows Shell.
Does anyone from Adobe frequent these forums still? Are there known trust settings I need to use when trying to print using the Windows Print Spooler?
Would it help if I opened a paid incident report?