Beta 2 has gone peculiar!

Help. I am not sure that this is the best approach to my problem but here goes......

I have been happily using 1.3, then the beta versions of 2.0 beta1 (since early December 2014) and 2.0 beta 2 (since mid January 2015), all very stable (well just the occasional drop out) until this evening when everything has gone haywire. It started with my virus protection (Avast) claiming the the mscore.exe file had picked up a virus and so it deleted it. After a lot of head scratching trying to find it and see what was going on at which I failed I completely uninstalled Beta 2 (this seemed to go OK) and went for a new download.

My system won't allow me to download the latest beta version. When I start the download it aborts with a message that "the connection was reset....".(plus some other stuff)

I luckily had kept the Musescore-2.0beta1 installation download in my download folder, so ran this and happily this installed. However, I can't now load my music files as my recent work was all done in the beta2 incarnation over the last couple of weeks or so. Older files do seem to load OK

So I thought how about upgrading? I see from the Help- Check for Update path that , yes, Musescore 2.0r.a925ae0 is available so off I go to the Musescore website, but I am once more greeted with the message that "the connection was reset...." I can't see that this is a problem with my home system as everything else is working normally.

I looked again in my downloads folder and found that again luckily I still had the MuseScore 2.0beta2 installer which I had downloaded in mid January so thought I would try re-running this file. All seemed to go well until it got to "copying new files" when once again my virus protection kicked in with a suspected threat. It said the exe file was contaminated by "Win32:Evo-gen" and so deleted the file. Sure enough, when I look in Program Files(x86)/MuseScore 2/bin the "mscore" exec file is missing so MuseScore won't run. The problem seems to be something to do with the latest beta 2 upgrade. Any advice???

Thanks in frustrated anticipation.