Can play released versions of Minecraft but not Snapshots

I can successfully play the released version of Minecraft but I get a crash whenever I try to use a Snapshot. I spent some time on minecraftirc.net this afternoon and re-installed Minecraft, deleted .minecraft folder, reinstalled Java (making sure it was not version 9) and quite a few other things they kindly asked me to do (they were excellent by the way).

We were finally able to get me running with the latest Snapshot after using the old launcher.

So it was suggested I file a report to you.

Please feel free to ask me anything you need to allow me to help.