
Glad to help you out with your learning curve. Seems to be going up exponentially so far.
As for the error, best to re-install that C++ before you encounter errors with the Avast! install. To do that, look in Add/Remove for the C++ program, uninstall that, have the downloaded C++ program handy, reboot, then install the new C++.
Re registry cleaners, the Windows Registry is extremely robust, and can tolerate many errors within it without apparent symptoms. Rather, it is the other way around, registry cleaners
can cause system damage so severe that the mildest form of damage is a slowdown, and the mid-range is installation errors, and worst, a dead system. Sounds counterintuitive, but this sort of program is snake-oil at best. You are right, you are the master of your system, but don't let that go to your head, and damage it any further. Remember, your computer is designed to do exactly what you tell it to do, and we often are the weakest link in the chain, and this is sometimes only due to simple ignorance.