As reported with the past 3 betas, the only workaround is to untick ‘monitor for unauthorized system changes’ in the behavior shield settings, otherwise Outpost is unable to start. Im just reporting again to make sure someone from Avast team sees it. 
If your version of Outpost 7.1 is 64bit, you should put that in your signature ?
Not even sure if there is a native 64bit version though.