I have a feeling that the issue may be coming from the hosting environment
of the Test Tool instead of the users' Direct implementations.
Looking at the dwFlags option in the link David posted
(http://msdn.microsoft.com/en-us/library/windows/desktop/aa379913%28v=vs.85%29.aspx),
both the possible padding flags require the presence of a newer/better
version of the crytographic provider for Windows environments (judging by
the Test Tool's OpenSSL command line I'm assuming its deployed on a
Microsoft OS).
I'm guessing that OpenSSL is internally trying to call CryptDecrypt (or a
nested call to something that checks padding?) with parameters it can't
understand.