Comment 3 for bug 345714

I tried switching ttys after I was kicked out to the Ubuntu login screen, and the same black screen with random color ascii characters occurred. However, it took several iterations of the greeter app restarting, plus me having to wait for a 2 minute timeout, before i could log back in. The following info was in /var/log/syslog during the time I could not login:
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Mar 19 22:41:51 laptop kernel: [ 4471.550198] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:41:51 laptop x-session-manager[10605]: WARNING: Detected that screensaver has left the bus
Mar 19 22:41:51 laptop gdm[10560]: WARNING: gdm_slave_xioerror_handler: Fatal X error - Restarting :0
Mar 19 22:41:52 laptop gdm[10560]: Mount of private directory return code [0]
Mar 19 22:41:52 laptop bonobo-activation-server (robbiew-11556): could not associate with desktop session: Failed to connect to socket /tmp/dbus-CVIWqWWvuc: Connection refused
Mar 19 22:41:53 laptop acpid: client connected from 11586[0:0]
Mar 19 22:41:54 laptop kernel: [ 4475.287600] set status page addr 0x04575000
Mar 19 22:41:57 laptop kernel: [ 4478.262718] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:41:59 laptop acpid: client connected from 11617[0:0]
Mar 19 22:42:01 laptop kernel: [ 4481.803993] set status page addr 0x04575000
Mar 19 22:42:01 laptop gdm[11637]: Gtk-WARNING: Ignoring the separator setting
Mar 19 22:42:04 laptop kernel: [ 4484.616267] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:42:06 laptop acpid: client connected from 11646[0:0]
Mar 19 22:42:07 laptop kernel: [ 4488.119864] set status page addr 0x04575000
Mar 19 22:42:08 laptop gdm[11666]: Gtk-WARNING: Ignoring the separator setting
Mar 19 22:42:08 laptop kernel: [ 4489.104757] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:42:12 laptop acpid: client connected from 11675[0:0]
Mar 19 22:42:14 laptop kernel: [ 4494.736541] set status page addr 0x04575000
Mar 19 22:42:14 laptop gdm[11695]: Gtk-WARNING: Ignoring the separator setting
Mar 19 22:42:15 laptop kernel: [ 4495.802798] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:42:23 laptop acpid: client connected from 11704[0:0]
Mar 19 22:42:25 laptop kernel: [ 4505.363256] set status page addr 0x04575000
Mar 19 22:42:25 laptop gdm[11724]: Gtk-WARNING: Ignoring the separator setting
Mar 19 22:42:26 laptop kernel: [ 4506.508980] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:42:39 laptop acpid: client connected from 11733[0:0]
Mar 19 22:42:40 laptop kernel: [ 4521.102949] set status page addr 0x04575000
Mar 19 22:42:41 laptop gdm[11753]: Gtk-WARNING: Ignoring the separator setting
Mar 19 22:42:42 laptop kernel: [ 4522.382258] [drm:gm45_get_vblank_counter] *ERROR* trying to get vblank count for disabled pipe 0
Mar 19 22:43:02 laptop gdm[4146]: WARNING: The display server has been shut down about 6 times in the last 90 seconds. It is likely that something bad is going on. Waiting for 2 minutes before trying again on display :0.