Unwrella is a completely legitimate texture unwrapping software plugin for 3ds max.
Available from here:
http://www.unwrella.com/download/Link is completely safe, it's a normal games and software company.
But trying to use the 'download unwrella 2 for 3ds max' link image - automatically gets stopped. In chrome as a network error, and the equivalents in IE and Firefox.
I had quite some issue before narrowing it down to Avast! being a bit overzealous, (I've updated to the latest version as of 11:24am CET 22/10/2013). I got around it by temporarily disabling all of my real-time shields, and sandbox.
I also had to do this to even create a backup - copying the setup file to an archive disk once I got it wouldn't happen unless all the shields were turned off. (windows 7, ultimate edition, x64)
Anyway - hope this helps future builds, as an exception or workaround will hopefully save a few other folks tearing their hair out for a while. (Other than that, love Avast! best anti-virus I've used).