It sounds like a bad install. I've seen incomplete downloads from Google that pretend to be complete, so be sure to check the size of the image file - should be 2Gb in size. There is also an md5sum listed on the download files page to check against, which will help you to verify the download.
One other thing to look for: when it is installing it will tell you how many blocks of data it is going to write, followed by how many it wrote. If those two numbers are different, you have a problem.
If you continue to have problems booting, follow these steps to see where it is getting hung up:
- Immediately after the Dell splash screen disappears, press the esc key to enter the menu. You only have 3 seconds to do this, so be ready.
- Select "Normal Boot" from the menu and press "e"
- Change the "gfxpayload..." line to read "set gfxpayload=text"
- Delete "quiet splash" from the line that begins with "linux"
- Press ctrl+x to boot
This will give you a very verbose bootup process. Let me know about any errors and what the last line says before it gets stuck.