I installed Dropbox and then it required Nautilus "to be restarted to function properly." When I clicked on "Nautilus Restart", my computer went locked up. Keyboard won't work and mouse arrow won't move around. I resorted to pushing the power button to shut the computer down. It happened in the previous version of Ubuntu 14.10 and then again in 15.04.
Is there a way to fix this problem? Your tips or help'll be greatly appreciated.