Hey Hernan! Good to see you around
Thanks for looking into the matter and deciding it's not simply avast (alone). As you know, I have many layers of security on my systems... so perhaps it's a
combination of the new avast being a catalyst to trigger one of my other security programs. Because there's no denying that having the x.2223 avast enabled (catalyst?) stops the MSRT on my XP system, but with the avast file-shield disabled, the MSRT will run. I never had any problems running the MSRT for XP under older builds of avast.
It's not the most important of issues, since there will be no more future MSRT versions for XP. But if I get a chance to "tinker", maybe I'll try to investigate further. Unfortunately, without any indication of warning/error messages, it may be difficult to analyze.
Thanks again.
EDIT: With avast's file shield enabled, I tried disabling MBAM Pro, MBAE Pro, and CryptoPrevent --- one at a time ---, but none of these changed anything. I don't know that I plan to try anything else.