Comment 1 for bug 507812

We need more elements to help you.
What is starting and what is not ?
Can you see grub's menu ? (where you can select ubutnu / recovery mode / maybe windows)
can you see usplash (ubuntu starting logo) ?
Can you see a login manager ?

To disable usplash for a single boot, follow these steps:
1. Press Esc during Grub boot delay to access the boot menu.
2. Select your actual Ubuntu boot line and press "e" to edit it.
3. Select the "kernel" line and press "e" to edit it.
4. At the end of the line, remove "splash" and "quiet" and press "enter".
5. Type "b" to boot the custom boot line.