It seems like you don't have permission in the custom directory.
Did you install it from a different user ?
You may need to run Toribash with administrator rights.
A quick solution will be to delete all sub folders from custom EXCEPT tori and uke.
Then just run Toribash and let it download the heads again.
I have Vista, i have the same problem. I don't think there is a fix, not one that works so you can run it like normal. I believe if you run as admin, it will autoupdate. Then just close and run as normal.