I ran across a window that (to me) look like an over-clocking slide for my graphics card so I increased by one notch. Ever since then I have had the problem of my PC just rebooting when it feels like it, it seems to me. I have never been able to find that same window again. My Graphics card is a NVIDIA GeForce4 MX 4000, bios version 4.18.20.42.61. HELLLLP!!

it sounds like the card is getting too hot so it restarts the pc. turn the overclocking settings back to how they were and it should be ok if you really want to overclock then get an aftermarket cooler e.g. a zalman heatsink, if they still make ones that fit your card

This is just a suggestion. If this is a new problem...use "system restore"... and go back to a date (a few days ago?) to when this was not an issue,and see if that does the trick. (I just REREAD your post). Whatever overclocking tool you are using, just put your settings back to default and let your graphics processor run normally.