My host is correcting this right now.
Could this ever be a search engine problem e.g. if your site has the old IP address of a bad site?
1. Different Countries - China, Saudi Arabia......
2. Filtering software (like the ones used in some libraries)
3. Isp's
My company is having a hard time finding an Isp with IP's unless they have a lot of adult clients. Apparently they grabbed them in the begining and are reisuing them now, getting new IP's is becoming very difficult.
And no I wouldn't use an IP that formely hosted Adult sites.