Unable to save overclocking freq from NVIDIA control panel

I don't know if this is a know issue but i can't save the overclock
frequency setting via nvidia control panel.
After testing the new frequency and check the 'apply settings at next
startup' the new setting is applied but not saved.
At reboot the new setting is not applied.

Also, changing the settings,saving and dismiss the drivers settings
dialog, returning to the panel i found them restored to default (the
board frequency clock are effectively changed but the configuration
panel is restored to default).
Then, how to apply at reboot the new clock settings with the drivers panel?

ps. I have a 6600 card, but with my old 5600 card was the same.
i used 50,60,70 series drivers but this behavior is the same for all
....also with the latest 80 series driver.

many thanks.
fabio.