I had an unlikely clash of bugs that almost had me reinstalling my system until I had a flash of insight. Here are the bugs that led to it. There's only two bugs, but they interact in nasty ways. 1. The ALSA drivers for the Sound Blaster external USB sound card do not like it when the Sound Blaster is positioned through two layers of hub. That is to say computer->hub->Sound Blaster is OK, but computer->hub->hub->Sound Blaster is not. (I've now experimentally confirmed this about a dozen times.) On startup, though, when ALSA is configuring cards, it will not complain. It will say "setting up ALSA card <whatever>" without a hiccup. 2. GNOME very stupidly will wait forever to play its opening sound when logging in. If the system refuses to play the opening sound, it will hang forever. You will not get that little bar which lists off the services being started (Metacity, Nautilus, et al). You will instead get a blank background screen (I'm still using the default), a mouse pointer and nothing else. Working out this bug took a long time -- mostly because I couldn't characterise it at first. I initially blamed some external hard drives, but that was a blind alley. It was only when I shutdown to single-user level and started up gdm that I noticed a) it logged in finally and b) it complained about HAL not being available. That's when I had my little flash of insight. To fix this, developers need to do one of three things: 1. Have ALSA work with the Sound Blaster card through two layers of hubs. (This may not be possible, depending on the Sound Blaster itself.) 2. Have ALSA recognise that the computer->hub->hub->SB layout is untenable and report that it is not allowed. 3. Have GNOME not wait for the sound to play before logging in. Or at least put a timeout on it. Still having fun with my all-Ubuntu system. ;-)