Windows – How to Uninstall Avast Free Antivirus

Open your Control Panel\All Control Panel Items\Programs and Features console and check if Avast is in the list of the installed applications. If not, then you need to re-install Avast. If it's listed there, then you need to install Visual C++ Redistributable for Visual Studio 2012 (VC110 is a code for C++ Visual Studio 2012). You can get it from here: Visual C++ Redistributable for Visual Studio 2012 Update 4

Make sure you install x86 and x64 versions side by side - note, you only can install x64 on a 64-bit Windows OS, so if it fails to install x64, then just skip that (no harm done).

I encountered this as well, even in safe mode. Turned out to be some rogue .dll file watching for anti-virus installers, hogging resources when it found something.

Assuming malware (or some other infection), I would try trojan hunter, or maybe search & destroy.

Trojan hunter is what finally worked for me.