Hi mate, I found this site searching for an answer as I was having the same issue on
newsgabAdbrite (the same ad providers used on this site) appear to be hosting dodgy ads.
Thanks for helping me with my troubleshooting, I removed the ads on my own site and this stopped the issue for my safari visitors, I guess its for the admin of this site to consider the same
I've also contacted adbrite advising them of the issue so hopefully they will sort it out either way
Cheers all, nice community BTW