PGP problems with large key rings?

I'm encountering problems when I try to form a large key ring (on the order of 150 keys, each with several signatures). The file is large enough (60+ Kb) but it is apparently trashed; when I run "pgp -kv" on it I only see 4 keys. This is under UNIX, so I don't think memory exhaustion is the problem. I'm not sure I have the latest version of the UNIX port, so if somebody could steer me to the right repository I'd like to try that too. Phil