anyone know all about colour

After all these years, I'm still not completely clear on graphics hardware &
software colour profiles.

If I "coloro-meter" my monitor, which creates a *.icm monitor profile -
which is set as the Windows default monitor profile all is lovely.

Then, if I want to reduce the video overlay brightness for playing a DVD -
as soon as I dig my way into my Nvidia software, and before adjusting
anything - the brightness level suddenly drops and is too dark - as though
the Nvidia software is knocking out settings held on the card, or perhaps in
software somewhere between the card and the Windows monitor profile. I
read a long time ago that the card holds settings ...somehow ...somewhere -
i.e. there's a "table" on the card, or that the card "refers" to, or "loads"

If I run the Nvidia monitor visual colour calibration, I end with everything
too dark - like gamma's dropped to 1.8 instead of staying at 2.2 - and it
all goes downhill from there !

I've stopped Adobe Gamme and Praxisoft WIZIWIG colour monitor profiles
fighting with each other, and stopped them loading at boot-up - and have
just one monitor colour profile set, in Windows - it's this sudden drop in
brightness as soon as I access the Nvidia grahpics card software (in system
tray) that's got me foxed ?

any clues gratefully received

regards, Richard
ps ...anyone who's got everything set in colour printing (graphics app. and
printer driver etc.) set to "automatic," and always gets a print that never
matches what's on screen - read everything at
http://www.normankoren.com/
....and you'll possibly attain that that glorious state, (just like like me),
where colour prints perfectly match what is on screen - but, then I fiddled
with it, and broke it ! ...just kidding - this is a fantastic web-site.