Re: Resolution problems with 8800GTX
hmm, that is odd.
It isn't that the card isn't good enough, my 29Pro can max oblivion at that res, and crysis runs reasonably well, albeit at lower detail settings.
Since it runs fine at 12x10, you can rule out heat, since the GPU won't get any hotter at 19x12 than 12x10.
The very high settings in crysis will be greyed out due to you running XP, rather than vista.
Have you tried reinstalling drivers, and tried previous driver versions? I suspect this to be a software problem rather than hardware.