I JUST NOW solved this problem. I thought I had it fixed by following the instructions (install as admin, run as admin), but after a reboot, no workie.
I located "TiVoDesktop.exe", "TiVoNotify.exe", "TiVoServer.exe", and "TiVoTransfer.exe" in the installation folder (ie. C:\Program Files (x86)\Tivo\Desktop), and set them to "Run as Administrator" on the "Compatibility" tab of the "Properties" menu.
Hope this helps.