Unfortunately currently Norton Antivirus often flags the windows installer as a virus, often this happens with each new revision until enough users report the issue as a "False Positive". So please report a problem with a false positive to Norton.
The way round this issue is to turn off Norton's 'Download Intelligence' while you install. On a new machine with Norton Antivirus 2012 or similar you will probably find this option on the advanced panel ( far left button ), on this panel there is a set of slders down the left and at the bottom is labeled "Download Intelligence", turn it off until you have installed haxe the default 15 min should be fine ( it will auto go back to protected after 15 min ).
We have placed the download files in a locked forum post so that the links can only point to the ones uploaded to the server by admin so that your are reassured.
If you have further worries you can compile from source or talk on IRC with active haxe users, and maybe get a user to make the latest haxe for you.