It's quite possible that your IP address is blacklisted. This server has been hammered by several hundreds of spambots and exploit scripts simultaneously in the past (most of it coming from China, Ukraine, and Poland), which did not really affect our security, but led to inferior performance and the necessity to block some IP ranges for the sake of keeping the service up in an acceptable quality.
Apart from the IP bans in the forum software that Morten refers to, which cover several /8 subnets (none of which your IP falls in, though), there are several other mechanisms that may be the reason for you being unable to access the site.
We have static rules in
iptables that block some very obnoxious IP ranges, as well as a combination of rewrite rules in the web server software which identify a few of the most stupid script kiddie exploits and will temporarily drop packets from an address that runs these.
Also, a daily cron script is updating a blocklist based on a combination of some local heuristics and a blacklist from a major DNS blacklisting service, dropping the top-100 offenders. Subnets which predominantly consist of hostile machines are blocked alltogether.
Most of the blocked subnets are /8 subnets with 120-150 attacking machines, or /16 subnets with more than 5000 attacking machines. Blocking these works very well, the shit-to-signal ratio has gone from nearly 95% down to under 1% that way.
However, certainly no system is perfect, and it may very well be that you can't access this site even though you are a normal, legitimate user who just happens to be in the same IP range as someone else who is scanning for exploits all day. We apologise for that inconvenience.
If you ever happen to get to know someone who is involved with that kind of thing (running exploits, sending spam), feel free to kick him hard where it hurts, and just to be sure, kick him in the face again when he's lying on the floor. This won't let you access this site any better of course, but you'll probably feel better
