Hi @leon_2,
I debugged through the login process and 4Shared is returning a 401 response when trying to authenticate.
My guess is that it is related to this: Bumblebee malware returns in new attacks abusing WebDAV folders - RedPacket Security
There is a malware attack that is abusing WebDAV to make it easier to load malware onto a victim’s machine. It doesn’t sound like an exploit or vulnerability of WebDAV, but because of the way Windows allows WebDAV to be mounted via Explorer, WebDAV is being used to distribute malware, once a user is tricked by a malicious e-mail and 4Shared was offering a way to do that via their free accounts.
4Shared probably disabled WebDAV access due to this.