Further to my posts about the problem with Windows XP and Avast antivirus 2015 R2SP2 (2015.10.2.2218), I tried to install it on another older computer, this time with an AMD Athlon XP 3000+ processor. This lacks the SSE2 instructions like the old laptops which I had previously tried to install Avast antivirus 2015 R2SP2 (2015.10.2.2218) on. This circumstantial evidence has convinced me that Avast techs may have assumed that all their users now employ 64-bit hardware and so, perhaps unintentionally, have prevented users of computers with 32-bit processors from running Avast.
Before resorting to AVG 2015, I took a copy of the Logs folder in C:\Documents and Settings\All Users\Application Data\Avast. Could someone at Avast please tell me if they would like me to forward it to them.