Eraser Portable and index.dat deletion

I am trying to use Eraser Portable to remove an index.dat file on Vista at reboot. When windows restarts, I get an error saying that Eraser has encountered a problem and needs to close.

I have tried this several times and occasionally it seems that the contents of the file are removed but many times it appears that only some of the contents are removed and the file size stays the same.

Is this just a feature that isn't possible since the app is on the USB drive or is there something I am doing wrong?

Thanks.