Trustdb Message

[Graham]

After I recompiled GPG 1.0.7 I was resetting my keyrings and trustdb
levels, and got this:

[xxxx@xxxx .gnupg]$ gpg --update-trustdb
gpg: 100 keys so far processed
gpg: [don't know]: invalid packet (ctb=03)
gpg: read_keyblock: read error: invalid packet
gpg: 100 keys processed
gpg: enumerate keyblocks failed: invalid keyring

As I have 249 keys on my keyring, which all seem to be imported Ok, and
they appear on GPA with keypairs being shown, so I assume that they've 
been imported.

I have looked up the documentation, and although I might have missed it, 
I can't find anything about invalid packets.  How do I know which key is 
the culprit and what does "invalid keyring" mean?

Any help would be most welcome
-- 

Graham
GPG Key ID: E935DB9D