Netpkg won't start in Zenwalk 5.2

I've had this problem a few times where when you click on the Netpkg button in XFCE Menu>>System, Netpkg just fails to start.
Trying it in a terminal (xnetpkg) gives this error:

Can't locate ZW/Netpkg/Netpkg.pm in @INC (@INC contains: /usr/lib/perl5/5.10.0/i486-linux-thread-multi /usr/lib/perl5/5.10.0 /usr/lib/perl5/site_perl/5.10.0/i486-linux-thread-multi /usr/lib/perl5/site_perl/5.10.0 /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl/5.8.8 /usr/lib/perl5/site_perl .) at /usr/sbin/xnetpkg line 19.
BEGIN failed--compilation aborted at /usr/sbin/xnetpkg line 19.

Luckily, it's easy to fix just by changing the mirror
# netpkg mirror
# 9 # this corresponds to the mirror at http://zenwalk.linuxish.net/i486/snapshot
# netpkg netpkg # upgrading the netpkg package
# 1 # say yes to everything i.e install upgraded netpkg and the corresponding perl packages.

Now netpkg should be available again.
See this thread for more explanations.