Hello,
I can say you're lucky in your misfortune
, as far I'm concerned I spent the last 72 hours to a similar issue with an "earthquake" in my registry.
Bad luck for me , no more restored points was aviable.
It happened after I wanted to do a clear install by the tool (firewall was unactif at the begining).
pc being frozen and non-responsive after the boot (even in safe mode , even in last good used config , even with recovery console on winxp CD).
At 2 fingers to ré-install OS , I boot with an other HDD , deleted used files "system","software","sam","security" and "default" from system32\config , replaced and renamed by files created in march 2013 by "tuneup" ? (named "SOFTWARE_tureg_old" , ....).
I 'am happy to see after 2 days lost time , my system boot again quickly , but it's not finished , I can see lot of some issues remaining.
at this time by example , even if I can open system tools (like system restore , users account , defrag , ...) I have just the windows with only white screen , nothing inside....
Well ... , I enjoy using avast when it works me too... I wonder if I have a better usable pc with or without anivirus
at least i don't have to pay for virus inside