Trying to open Secured PDF from VB

[JR]

Can anyone explain this PDF & Visual Basic issue to me...?

I've got a PDF manual that I received from a vendor that's password
protected against changes, but can be viewed and printed.

If I do a Start | Run | g:\test\manual.pdf, the file opens in the Windows
associated program (Acrobat Reader) with the titlebar showing "Manual.pdf
(SECURED)".

When in Visual Basic, if I issue a ShellExecute command that basically does
the same thing, but I get a "File Not Found" error returned and Acrobat
never opens.

I know the VB code is correct because on non-password protected pdfs, both
ways work identical. I don't understand why it'll open using Windows just
fine but when called from VB it errors.

Any help would be greatly appreciated. Thanks...JR