NEED HELP ASAP INSTALLATION PROBLEM!

[cavedweller88]

I have just switched my ubuntu desktop to linux mint via usb thumb drive. Installation seemed successful at which point it asked me to restart the computer which is normal. On the restart the boot drive promt came up and the only options were Start Linux mint(which ii'm pretty sure only leads to the virtual os) and Start Linux mint Compatiablity test(after test also leads to virtual mint os) Check the integrity of the medium and test memory. At that point I turned off the computer.. removed the usb thumb drive and restarted my computer at which point a threatening looking screen that says " selected boot image did not authenticate. press enter" I hit enter and the computer shuts down completly.

I rebooted my computer and used the virtual mint os and on clicked the install icon the desktop for installation and in the promt for partitions and what not it asked if i wanted to replace my Mint nadia edition with mint nadia edition...So doesn't that mean that my computer is already Mint nadia?

Very comfused...Please help and understand I am a noob when it comes to Linux

Thanks in advance!

[viking777]

You give us so little information about your computer that your question is virtually impossible to answer, so I will take a wild guess. Does this computer have, or has it ever had Uefi or Secure Boot on it?

If the answer is yes, go into the bios at boot up, switch them both off (if you can, on some bioses this is not possible) and then install mint again.

Edit. In fact you might not even need to reinstall, the original installation might possibly work once those two are switched off.