Avast has never flagged TPT on my system, but if it is flagging it on your system, make sure a virus has not actually infected the executable and then add an exception in the settings of Avast for TPT executable.
@Dingolo(View Post) yes, there is a little box under the sand box/normal options, click on that box then will apeare a tick there its all :) just copy url from video
Obviously, its not powder toy. TPT is working you permissions and/or firewall is not letting you open it because of a threat. Have you triead turning your computer off and back on? What did you do last on TPT?