I figured out the problem! Mine anyway, and probably the same issue you are having. I emailed Nvidia about the issue and this is what I got back:
"If you wait for roughly a minute, does X finally start?
You may be experiencing the following problem, which was especially
prevalent with some GeForce3's:
Q: X takes a long time to start (possibly several minutes). What can
A: Most of the startx delay problems we have found are caused by incorrect
data in video BIOSes about what display devices are possibly connected
or what i2c port should be used for detection. You can work around
these problems with the XF86Config option "IgnoreDisplayDevices"
(please see the description in (app-d) APPENDIX D: XF86CONFIG OPTIONS)."
Indeed, I left it starting for a few minutes and X finally came up! The solution is pretty simple, you just have to edit /etc/X11/XF86Config, under the monitor section and add:
Option "IgnoreDisplayDevices" "DFP, TV"
That just tells it to ignore the DFP and TV out ports. (If you have a digital flat panel screen connected to the dvi port, tell it to ignore "CRT, TV")
Here's a link to the Nvidia Linux driver readme with more information if you want to read more about it (Look in appendix D):