I was running into the same issue... when I plug the TB into my Win7 64 laptop it would give me the options to mount, but the computer would add a cd/dvd drive as the E: drive. This only gave me access to some install files (about 5.8mb). now I already have several networked drives including an F, L, S,T, and Z.
What I found out is that the TB is actually mapping over my networked F: drive as a USB drive, but not changing the name. So If i double click on my F: drive, it will give me access to my TB.
I discovered this by going to the device manager and looking at the "portable devices". there it showed me "F:\" as an option.
I'm just happy I have access to my TB... but does anyone know how to fix this issue?