I'm connection to my Mac Mini from Windows, using RealVNC client (also tried TightVNC with the same behavior).
And, Login Screen shows fine, but when I'm typing password sometimes it hangs. Also it hangs when I successfully typed password and pressed enter. However, occassionally it allows me in (especially after restarting ARD or restarting Mac OS). Also, when it hangs after sending password and pressing enter, actually VNC connection is established - when I moving mouse on Windows, it also moves mouse pointer on Mac OS.
Where can be a problem, and what I can do to debug this issue?