Thanks for your reply
I have checked the forum error logs, and theres nothing in there at all that are generated from guests or that IP.
The time online is set to 15 minutes (but this particular "guest" was refreshing 2 or 3 times a minute)
We're using 1.1.10, but the forum is just one part of the site, and we dont see people on the who's online until they actually go to the forum rather than the other part of the site, then if they stay on the main site for more than 15 minutes, they drop off the forum.
All I can think of is that its some hacker trying to hack the CAPTCHA, but in our case our forum doesnt have CAPTCHA... but if that is the case, it would still be nice to know what they are doing
Does this all make sense? (sorry, its early, and I've woken with a headache

)