Nobody likes malware. Correction: nobody with a soul likes malware, which effectively excludes malware writers and script kiddies who find it monetarily beneficial (the former) or just plain amusing (the latter) to spread infected files. Microsoft certainly isn't amused by malware and has built a tool to help restore systems ravaged by rootkits and other cruft.
Windows Defender Offline Beta is a new security tool Microsoft has made available to help remove hard to find malicious software and potentially unwanted programs (PUPs), such as rootkits and advanced malware that might slip past anti-malware programs.
Microsoft's free beta security tool initially is a small download that creates a bootable CD, DVD, or USB flash drive. You will, however, need 250MB of free space for the program on your optical or USB media to store the program and definition files, and an Internet connection to download said files.
You can check out the related FAQ here and download the beta software (32-bit and 64-bit versions available) here.