the same problem
After initialization of nvidia module and graphic mode by the X all attempts to go back to text console (vt1-6) failed because of too high horizontal frequency used. In my situation the frequency is 165Hz, which my monitor cannot handle.
I have DDC-enabled monitor, XFree86.log lists correct ranges for it.
This appears only after initialization of nvidia driver, boot screen is okay.
I have GeForce4 MX440 with no attached TV.
The question is how to set correct vrefresh for text mode?