First off, yes I know you need to be running WinMFS as an administrator. I am.
tl;dr: WinMFS won't see my new WD20EARX. Help?
Setup: Tivo HD, Macbook Pro, USB <-> SATA adaptor, running windows 7 in VMware Fusion.
Full story: Upgraded my stock 160GB -> 500GB Seagate barracuda a few days ago using WinMFS. Process was easy, WinMFS saw both drives fine. Put Seagate into Tivo, but it turns out the drive is too loud. It filled my living room with HDD noise, so bought new WD20EARX.
Started again with original 160gb drive, backed up using DvrBARS, restored image to WD20EARX using DvrBARS. Worked great. Put WD20EARX into Tivo. Boots and reports 21HD hours (as expected). Connected drive back to computer to use WinMFS to expand drive, but WinMFS doesn't see drive. Even when I check 'show mounted drive', no drives show up.