Beginning with the gentoo-dev-sources 2.6.7-r4, and r5 the Nvidia kernel module will freeze the computer when loading the gdm at startup or any other time. Didn't not appear in gentoo-dev-sources 2.6.7-r3. System freezes, and only way to get fuctioning system back is to press the reset button or turn off power.
Go bug the nvidia people about kernel freezes. It looks like they just released a new version. Nothing we (the kernel group) can do about nvidia issues, sorry.