http://www.icyphoenix.com/viewtopic.php?f=35&t=4491&p=30311#p30311
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Lopalong
Tue 05 Aug, 2008 08:25

Re: Users Can't Be Registered
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ACP -> Server ->

Make sure this is set to YES.

[quote]Disable public blacklist IP check upon register
If you disable IP check upon register, then IP's will not be checked against the public blacklist. Disabling this may be useful, because sometimes this check may result in unintentional blocking of regular users who have an IP listed by mistake in the public blacklist.[/quote]