I switched from 32 bit Ubuntu (where it worked just fine) to the newest 18.04. I own quite an old computer HP compaq nx6310 with Intel Mobile 945GM and now I am able to boot only through recovery. Is it a driver issue? Is it even compatible? Where to get that driver?
Regular ubuntu no longer supports 32bit processors like yours unfortunately, you may want to consider trying Lubuntu 18.04 which still does.