keys beginning with zero-octet mpi's

[vedaal]

i recently had a proble with a v3 rsa key imported from pgp to gnupg 1.0.7.

after importing it, gnupg would give error messages about
'mpi being too large'

i forwarded the key to someone who reported the same problem with it, and
forwarded the key onto the gnupg devel list,

he forwarded the answer to me, that:

"It's probably an encrypted MPI started with a zero octet.  This
problem is already known, I think.

Workaround: Create a new directory, copy the secret key (in
non-armored from) to "secring.gpg", use "gpg --home . --edit-key" to
change the passphrase.  It's likely that the result is readable by
GnuPG (the bug is triggered with a probability of 1:85 or so)."

i did this, and after changing the passphrase and importing the key, it
worked fine.

my questions now are:
How can one tell when one's key begins with this type of problem octet?

Is it the same frequency for all key types?
{the key in question was a v3 rsa test key,
can post the original problem key here, with the passphrase if it would be
helpful}

TIA,

vedaal