Convert the entire MBR to a GPT file, keeping just the partition details.
Convert the entire MBR to a GPT file, keeping just the partition details.
Clean will erase everything on the drive, so it's best to back up your files first. It might be simpler to go into UEFI and check for CSM or Compatibility Support Module (on MSI boards this is Windows 8/10 Install Mode and should be turned off). Turn that on then open your boot menu and select the non-UEFI boot option. This should let you install on an MBR partition.