Use a virus scanner. Dozens of people on this site can testify the official distribution of WinMFS from http://www.mfslive.org is virus free. If you really have a bug up your butt about it, use MFS_Live. It's a linux distro on a live CD. Linux does not have viruses. Then re-load from your backups. WinMFS won't screw up your computer settings. Extremely poorly. Not at all if you have a LAN server. Or a decent OS. The MAK allows TDT to log in and download information and files from the TiVo. I suppose you could, but that would pretty much defeat the primary purpose of the MAK. That, plus the previous owner should never really share his MAK with you, or anyone else. Neither should you. A much better solution is to call TiVo and have the new TiVo transferred to your account, at which point in time (well, within 48 hours) it will obtain the same MAK as the other TiVo on your account. Note the MAK doesn't really have anything directly to do with TDT, per se. The MAK is required when logging in to the TiVo from any utility, including kmttg, pyTivo (for pushes only), streambaby, HME for Python and any of its tools, another TiVo, or any old web browser. It's also required for TDT. Here I am logging in to one of my TiVos using a web browser (FireFox): The user name is "tivo". The password is my MAK. Every other TiVo application that attempts to contact the TiVo using SHTTP, including TDT, does the exact same thing behind the scenes. The MAK is also used as an encryption / decryption key for decrypting .TiVo files. Again, this is true no matter what utility is doing the decryption. Note if you download any shows off the new TiVo when it has its old MAK, then those files can only be decrypted using the old MAK.