Is miata.net Safe?

I tried this site, and it locked up my opera browser. I thought it was a browser issue, so I tried firefox, and it locked up firefox even worse, to where my computer was completely locked up, and wouldn't restart properly. I had to restore my pc to an earlier date, and then uninstall, and reinstall firefox. I then stupidly tried the site again, but when it locked up this time, I manually shut my pc down quickly, and when it restarted everything was ok... Never again will I come here. My antivirus didn't make a peep, so I don't know what the problem is.