Is this the Dell Trusted Platform Module BIOS setting which enables encryption? If so you can turn it off in BIOS setup.
If not, Let's start by getting a clean boot so nothing is running except the OS and your AV.
Enter msconfig>Startup and uncheck everything except your AV listing.
Next enter msconfig>Services, select Hide all MS services, then uncheck all except AV.
After several reboots check back in both places to make sure nothing wrote itself back in. If so, turn it off in it's Program preferences or Uninstall it. You can learn what program is involved by googling the listing.
If problem persists, google the exact error message verbatim to learn how others have solved it.
Run a full scan with Malwarebytes.
Install recommended MSE or Avast 6, run full scan.
If you have one of the bloatware AV's MucAfee or Norton, uninstall using their special tool.