サイト自体へのアクセスは問題なさそうです。
http://safeweb.norton.com/report/show?name=instantdownloads.net
ですが、以下のように詐欺サイト(unrestrictedownloads.com)へリンクしているという情報があります。
http://www.complaintsboard.com/complaints/fraud-c387198.html
I searched for a book on google and clicked on the link to that website. It asked me to purchase 34.88 AUD for 1 year unlimited download. I've tried to search for the name of the website before purchasing and there's no negative information about that website. However, after being a member, the login and download site all link directly to unrestrictedownloads.com - a scam. Already talked to my company credit card, but the transaction had been done. So frustrated.
この「unrestrictedownloads.com」については以下の情報があるので信用できないと思った方がいいと思います。
かみさま