Richard, why your own pc doesn't work is most likely because of the authentication cookie stored. Since I altered your log in name, the cooke doesn't match, and you need to sign out and sign in, again for it to work - besides, uncheck the sign in always flag, so the cookie is not persistent.
Regarding your other comment of certain names ... "beware" ... let's get down to facts:
The community has blocking on Names and IP, and rates a posters posting spam count.
Disallowed names are stored as wild-card combinations, f.ex. *pmail*, meaning no one can enter an address, or nick name containing any combination of pmail. Plus all sorts of swear words, slang of lets call it "red" content.
Banned IP:s is simply a list denying traffic from/to certian IP ranges, or individual IP numbers. Only very few IP numbers are banned.
SPAM count, in postings - First of all, when the spam count is reached, a posting is tagged for moderation. Then it has to be manually approved. F.ex. containing some bad words, a couple of links etc. The spam count is calculated on 1: Bad word count, 2: Link count, 3: IP Count (a calculated floating average based on posting ip), 4: Forbidden word.
I've only tuned these settings slightly since the shipped defaults seem to do the job quite well.
A few years ago I had some Australian friends over - they 
on the freeway at signs about automatic Fartkontrol 
and burst into BIG 
when we stopped at a GatuKok 
for a hotdog.
// Fartkontrol = Speed control && GatuKok (Alligator ...) = Street Kitchen
Kind regards / Peter