I think “1d” is the illegal instruction “code”, not an address. It’s weird most users are running just fine on various
flavors of Athlon XP. As far as I know they all support SSE instructions but not any of the later extensions.
At first glance it would appear that either avast tried to execute an instruction that did not exist on those old CPU’s
or there was some other error and the program took a wild branch and tried to execute garbage.
either way, I’m surprised we haven’t got a answer from the avast team by now.