I had a similar problem, and I have solved it downgrading from Crypt-OpenPGP-1.06 to Crypt-OpenPGP-1.04

The reason for this is that version 1.06 uses Math::BigInt where 1.04 uses Math::Pari for big numbers

When a private RSA key is extracted from the ring, the components are stored in Math::BigInt objects, and at some point it are used with a Crypt::RSA::Key::Private objects, that internally uses Math::Pari objects for the components

When the Crypt::RSA::Key::Private::AUTOLOAD method is called for component creation with a Math::BigInt object reference as a parameter, it fails. The component is't updated, but no error is reported

Later, when the private key is going to be used for decrypt, it fails because it doesn't have the private components

Hope this help