It looks like a video issue. Please try to boot the computer to "Safe Mode with Networking" and check. To boot to the Safe Mode with Networking:
1. Power on/restart the computer and start hitting the F8 key as soon as the initial startup logo appears.
2. Advance Boot Menu will appear. If the menu doesn't appear once, repeat step 1 again.
3. Select "Safe Mode with Networking" and hit Enter.
If the video is good in "Safe Mode with Networking" try to download and update the video drivers from here.
Do reply with results.
To know more about Dell's products, services and drivers & downloads, please go to http://dell.to/YBlak6