Help Yourself Get Rid of Win64:Bot-A [Trj]

Complaints about Win64:Bot-A [Trj]:

Case one: Help!  I'm on a PC, Windows 8.1, 64 bit OS and just the other day, I kept getting pop ups every 30 seconds that there was a threat detected of rsa64.dll file.  I've done full scans, even downloaded Malwarebytes Anti-malware and both quick and full scans on Avast do not reveal the infection.  And yet I look at the quarantine folder and there the files are.  And when I'm on the desktop mode, it keeps flashing right before the pop up for threat detected comes up.  Help?

Case two: HI, I'm getting warnings every 5 sec by Avast saying that this file: C:\ProgramData\Microsoft\Crypto\RSA64\rsa64.dll (or these files: C:\ProgramData\Microsoft\Crypto\RSA64\temp\* ) are infected by said Trojan Win64:Bot-A [Trj].I'm running win 8 64. I am unable to download Malwarebytes' Anti-Malware.
Can somebody help / give a hint? Many thanks!

How harmful Win64:Bot-A [Trj] is? 

Win64:Bot-A [Trj] is a malicious Trojan horse which will destroy the operating system gradually. After being infected with Win64:Bot-A [Trj], computer users may encounter a lot of computer problems, such as the poor running speed, windows freeze and even the system crash. To protect itself from being removed by antivirus software, Win64:Bot-A [Trj] modifies the registry entries and files that stored in the system and mutates frequently to add new characteristics.