You're not alone -- if you check the NT forums, you'll see others reporting the same problem. Reloading the data, repairing the DB, and standard data "fixes" don't make these phantom bars go away. NT is saying it's Zen's fault.
There's no way I know of to remove just the saturday bars (although I think NT7 has that capability). So it looks like we're stuck with them unless Zen deletes them. Same goes with most other instruments, except TF.
Just when are they releasing NT7 anyway? They cried wolf on so many occasions by announcing it's about to come off the assembly line only to have it delayed time and time again, I have no faith in them anymore.
Anyway, I ain't trading tonight so I'm not too concerned.