i know what you mean.... sadly to nVidia its more important to bring up new things in the drivers then releasing a stable 2D driver for Linux.
Nearly everyone with newer cards are having problems with hibernate or the powermizer.
At nVidia they say they cant reproduce the problem.... good excuse, cause when you say that, there is no problem.... what you cant see you cant fix.
Little bit childish, but thats the way it is!
Im having problems with both hibernate and the powermizer, do i have a exotic system you will ask? well just Fedora 8 with a GTX 260.
Im struggeling with problems since i got the card and that was in November, now end March (5months later) still have the problems.
I have giving up hope on a stable 2D for my card
There are to ways to solve your problems:
1 Use the very stable VESA driver, wich is much better then the nVidia driver in 2D (dont laugh its really true)
2 Buy a ATI card, they can provide good driver support on their products and if you have a problem they listen and give support.