To clarify - is this issue only occurring in XP Pro?
I remember when trouble shooting my computer boot up problem where it was freezing when launching services I found it was related to Avast services and the work around was to select to haver Avast services started after all other services had started. It solved the issue.
I also read in that thread and seen it mention in other threads that the new version of Avast wasn't tested as thoroughly as it should have been with XP.
I don't know where you get your stats from to say "Avast wasn't tested as thoroughly as it should have been with XP" and speculation within the forum certainly isn't proof. There were many regular forum members who are XP users involved in the longest duration beta testing for the new program version.
I think that in all there were 100,000 who partook in the beta testing, I don't know what the breakdown of OSes is, but if it is anything like the overall market share of OSes, then XP should have had reasonable representation. But, the only people who could possibly confirm numbers are avast.
Of course there was nothing to stop you from participating in the beta trial.