Every few years I rebuild my home theater computer. It has an older NVidia GX220 or something model card in it. Ubuntu never wants display the desktop correctly. Today I found that the “nosetmode” switch from the F6 menu was not successfully adding that word to the boot command so I had to type it in manually. Once done, the Desktop would appear correctly.
Behind the F6 menu is the Boot Options command. Cursor over to the end where you find “quiet splash” and add “nomodeset” before “quiet” and all was well again.