Key Import Error

[Ken Ferguson]

I'm trying to import a pgp key and getting an error I know nothing about.

gpg --import D:\keyfile.key.pgp

gpg: mpi too large for this implementation (40843 bits)
gpg: mpi too large for this implementation (43184 bits)
gpg: read_block: read error: invalid packet
gpg: import from `D:\keyfile.key.pgp' failed: invalid keyring
gpg: Total number processed: 0

Does anyone have any idea what this means??? I have another key in a 
.txt file and it imports perfectly fine. I'm a total nube and any help 
will be greatly appreciated.

TIA,
Ferg