A little update on my situation. I was using my old 9600gt for the last 3 month, but upgaded motheboard a couple of days ago and decided to give 460 a try again, and got interesting results. First, no "NVRM: os_pci_init_handle: invalid context!" and no problems with ctrl-alt-Fx. Same kernel/driver/xorg, only mobo is different. Unfortunately, now i am getting random dead freezes, very similar to what other people reported in that thread http://www.nvnews.net/vbulletin/showthread.php?t=158172
. It's really a dead freeze, so no bug-report, system just freezes complete with no response to anything and there nothing at all in logfiles after reboot. Again, as with old mobo, no problems in windows, and no problems in linux with 9800gt.
I am inclined to the idea that there are some video cards bioses out there that are somehow incompatible with linux driver...
I will try to exchange asus for 460gtx from another manufacturer and report back.