Hello,

I really appreciate that you have ran the hardware diagnostics and provided the results which proves that the hardware components are fine. I would suggest few steps which might fix the issue.

1. Check in Safe Mode.
-- Restart the computer.
-- Keep tapping F8 on the Dell Logo Screen.
-- Once the computer enters Advanced Boot Option, select Safe Mode.
-- Press Enter.
-- Check if the computer is booting into safe mode.
If the computer boots into safe mode, I would suggest doing a System Restore.
In case system restore doesn’t fix the issue follow step 2.

2. Run Start Up Repair.
In case Start Up Repair doesn’t fix the issue, we would have to do a PC Restore.

-- Performing a PC Restore (Factor Image).
Doing a PC Restore would take the computer to the original factory settings.
Please follow the link mentioned below to perform the PC Restore.
http://dell.to/KTY2az

**NOTE: Please ensure to back up all the data from your computer before performing the PC Restore as it would erase everything from your computer.
Please try the steps and write back with results; I’d be glad to assist you further.

Alan,

I tried what you said but couldn't even do the first step. I keep hitting F8 but can't get the advanced boot options. I tried like a hundred times. I can go both to Set Up (F2) and Boot Options (F12), but not F8.

Also, I don't know if this is useful but after running the Diagnostics on the memory I get: "Boot Diagnostic Utility Partition. Press any key to continue."

What should I do?

Tks

Hi, 

Thank you for replying.
It would definitely  suggest you to get into the Boot Diagnostic Utility Partition to run the Custom Test on the hard drive. Refer to the link mentioned below which would help you to the custom test on the hard drive. 
http://support.dell.com/support/topics/global.aspx/support/kcs/document?c=us&cs=19&l=en&s=dhs&docid=DSN_A9E3A15597A04AFBB02EE16785D39C5C&isLegacy=true

Please write back to us if you have any further questions.

Help me out here please:

When I press F12 I go to the Boot options, Diagnostics... then this:

1. When the Boot menu appears, highlight the Boot to Utility Partitionoption, or the Diagnostics option and then press   to start the  32-bit  Dell Diagnostics.  
2. Press the   key to highlight  Test System Press   to continue to 32-bit Diagnostics.

Hi,

Apologies for the late response.
When ever you get the message "Boot Diagnostic Utlity Partition. Press any key to continue", press Enter and it would enter the 32-bit Diagnostics.
 

Hi,

When you get the screen with the tests, we need to select the test that we intend to run. We can select the test using the up and down arrow keys or mouse and run the test. I would suggest running a custom test on the hard drive.
-- From the list of the tests, select Custom Test, and then select the hard drive. It would run the test on the hard drive.

Please write back to us if you have any further questions.