I am running Ubuntu 12.04 on my computer. Yesterday I tried to change the splash screen according to the instructions here here.Then I installed gdm. After that I restarted the computer and the splash screen was changed. I enabled automatic login. Then I restarted again and went into windows 7 and again came back to Ubuntu.

This time Ubuntu was stuck up at a black screen with the following message:

                                    Ubuntu 12.04  

                                ....*starting virtualBox kernel modules       [OK]

*stopping cold plug devices       [OK]

                                  [OK]*Stopping log initial device creation 

                                  [OK]*Starting configure network device security  

                                  [OK]*Starting save udev log and update rules  

                                  [OK]*starting configure virtual network devices

                                  [OK]*Stopping configure virtual network devices 

                                  [OK]*Stopping save udev log and update rules [OK]



                                      *Starting Network connection manager wicd 

    *Starting the winbind daemon winbind                                            [OK]S

aned disabled:edit /etc/default/saned                                               [OK]S

tarting HWActivator *[done]

                               *Starting TiMidity++ALSA midi emulation...          [OK][ 

23.184121] usb 1-1.5:device descriptor read/64, error -32

[23.359845]usb 1-1.5:device descriptor read/64, error -32

I have reinstalled Ubuntu now, but I just want to know what caused the problem.