I turn on the laptop the dell logo boots then the screen goes blank a padlock is illuminated on the panel . What is going on?

Contact the authorized service center for DELL.
http://electronicshelponline.blogspot.com/
http://electro-medical.blogspot.com/

You can try to boot to safemode. When you turn on system as soon as you see Dell logo keep tapping F8,select Safemode under advance boot option. If you we're able to log in to your account you can try to uninstall video driver and restart the system to normal mode then reinstall the video driver.
If you we're not able to boot to safemode , you can try to connect to external monitor toggle to FN+F8 if still not showing anything might be a bad video card.

After the logo flashes, press F8, repeatedly, until a white-over-black "boot menu" is displayed. Choose "Safe Mode", to see if this "minimal" version of Windows will startup successfully.

try booting in safe mode and do system restore up to the last good working date of your laptop. . .
hope this helps.

Try booting to the safe mode (F8 at boot) and see if you can log in via the safe mode. If you can't, try booting to your Windows CD, go to recovery console and run CHKDSK /R
If you still can't log in, try running diags see if the hard drive lists a failure.
if no hardware failure found, there and none of those solutions work, then re-installing windows will likely be the final resolution

First you'll have to power off the system.
Please power on the system and as soon as you see the Dell logo please tap the F2 button 3 - 4 times.
The computer will go to the system setup. Check if the screen goes blank here.
If the screen stays on then try this.
1. Please power off the system.
2. Please power on the system and as soon as you see the Dell logo please tap the F8 button 3 - 4 times. You'll reach the Windows Advanced Boot Options Menu on the screen.
3.Select Safe mode with Networking.
4. Select Administrator at the log in screen.
5. Warning dialog box with the message Windows is running in safe mode. appears. Click the Yes button.
6. The desktop appears with the words Safe Mode appearing in all four corners.
7. Uninstall the video drivers and restart the computer.
8. Resintall the video drivers.

Rate if useful.

I had that happen to me with my Dell as well... If you're comfortable with taking a laptop apart.. you'll need to detach the screen ribbon, clean it with rubbing alcohol, and then reattach it. This should do the trick..

windows is not loading properly.
if you're not worried about anything on the computer:
insert the recovery CD, boot the system to the CD, and reinsatll windows.

plz try to boot through safe mode, if you can then log in normally.
if you cant boot from safe mode then you have to reload or repair your os.

It is better to run the dell diagnostics, when you see the dell logo keep on tapping f12, then choose utility partition and do an express on your system.