Why does synchronization with Vagrant not work in Windows 7/Windows 8, freezes when accessing or moving to a synchronized folder?

Question

virtual box

Ubuntu 13.10 image
cloud-images.ubuntu.com/vagrant/raring/current/rar...
cloud-images.ubuntu.com/vagrant/saucy/current/sauc...
In Vagrant, it is written to synchronize folders:
config.vm. synced_folder "C:\\web", "/home/vagrant/web"
Folder C:\\web is initially empty, /home/vagrant/web is created automatically or empty.
vagrant up
Everything starts and connects ok.
But when you try to go to the /home/vagrant/web folder, the ssh or WinSCP client (any ssh client) hangs stupidly.