I uninstalled 2.57 to make way for 2.57b and noticed the uninstall also deletes user created directories in the install directory. Its not too serious in my case as its just tutorial & experimental stuff I lost, but for some users it might be a problem. Most uninstall programs doesn’t remove user created subdirectories. You get a warning about what its about to remove but clicking no doesn’t change anything - everything gets removed anyway. There is no way to abort the preocess.
You should have just let 2.57b install over 2.57