Re: 64 bit installation problems
What video do you have? If you have nvidia, you may need to use nomodeset to boot install iso (or at least I did for PC in my sig). Although, I did not need an parameters once installed.
My early Athlon64 3200+ (2 GHz single core from 2004) runs 64-bit 10.04 which I have not updated yet. But it boots normal 64-bit 12.04 live/install on USB stick fine with 2 GB RAM and its legacy ATI video (X1300). It is missing the lahf_lm instruction for true 64-bit flash, but someone made a plugin for that so it would work. Many years ago it ran 64-bit SuSE.
Strangely I had trouble doing a normal 64-bit 12.04 install to my laptop with 1.66 MHz Intel Core 2 Duo w/2.5 GB RAM, integrated Intel video. It would hang indefinitely (for hours) at 90% of "Installing system" with no errors. Alternate 64-bit install worked fine.
i5 650 3.2 GHz, 8 GB, nvidia GTX 550 Ti @ 1080p (year old GT 430 began freezing) and assorted other computers