This is weird.
I installed the latest version (12.1.2264), then I rebooted and it failed to load components. When I tried to repair the install, it failed to load the language.dll, saying that it was looking for it in a folder called "1033", but it was in a folder called " 1040". So, I rebooted in safe mode, I copied everything that was in the "1040" in a new folder, which I renamed "1033". Then, I rebooted in normal mode and everything was fine.
OS: Windows XP Professional SP3 - Extended Support
AV Version: Avast Premier Beta 12.1.2264. (Paying user and beta-tester).