I also got a new computer yesterday. I installed avast , and have the same problems with the IU, plus it also says avast is down and says I'm in danger. I have been trying to fix all day. I have tried the clean and reinstall . tried it with airplane mode on , I even tried a fresh install of windows with all the updates and then installed avast no other installs. same problems. My event logs say avast services terminated unexpectedly over and over. I also have a red x in the icon all the time unless i restart avast. it comes back on but stops after a few minuets. I'm using windows 10 Pro version 1709 build 16299.98.
I'm not having this issue with my other windows 10 machines.