I am running a 64 Bit Ubuntu, AMD quadcore, with 4gb of RAM and a Nvidia gtx260 graphics card. The issue is as follows:
Once Ubuntu has booted and I get to the login screen, my screen goes black and I hear the login sound. This is often spontaneous; sometimes it loads as it should, and others it goes black. Previously to login, I would restart my computer until the login screen successfully loaded, and after 4-5 attempts I would get it working. These days I use Ctrl + Alt + F1 to access the command line and use the following command
sudo /etc/init.d/gdm restart, but again this can take sometimes up to five attempts before it successfully displays the login screen.
I have previously googled this problem, and attempted many of the proposed workarounds (editing the xorg.conf file etc.), and none have worked. My guess is that the proprietary graphics drivers are at fault (as the Plymouth theme is the wrong size and ugly also). Is there proper workaround for this? if so, please let me know, as it can try my patience immeasurably and could potentially cripple a First-time-users experience.