I just tried downloading Bitcoin Core from bitcoin.org (the link on the top of this site). My antivirus software suggested it was unsafe and removed it. I then downloaded Bitcoin Core version 0.13.1 which downloaded fine and was classified as safe when scanned with antivirus software. (I looked on virustotal.com and found that none of the FREE antivirus service have suggested that it has a virus or is a dangerous file).
This may just be that the bitcoin core has only recently been released today (the 0.13.2 version).
Hey,
Bitcoin Core 13.2 is brand new. Less than a week old. So, anti-virus software doesn't know what to do with it yet, so it deletes it.
Maybe in your case, it was Norton 360 or security suite. It doesn't say it is a virus. It says it may be unsafe and deletes it. You can restore it and install.
Or, if you want to wait for Norton to figure out what's up, you can simply install 13.1 since Norton has figured out it's ok.