I can't find any trace of "seed" in perlapi either. For a core module, that's bad, IMO

It may be a deficiency in perlapi. 'Perl_seed' is in embed.fnc (as the entry 'Ap|U32|seed' .... something I learnt from the response to a follow-up post I sent to the xs mailing list) so it really ought to be available. The fact that it's not available in PXPerl really does sound like a PXPerl bug. There's certainly no problem there with ActiveState perl (or any of the other Win32 perls that I have).

Cheers,
Rob