PCIe video card not working after SP1

my configuration:
mobo: Gigabyte AM2 MA69VM
processor: AMD 4200+
RAM 2 x 1 GB DDR2
graphics nvidia 8400 GS

Software: VISTA ultimate 32bit
I use this computer to do some basic office stuff and multimedia things, like
- surfing the net
- word
- playing movies from my NAS on my television

before i installed SP1 everything was working fine,
so now i installed SP1 for vista and it when it boots, i get the running bar, just before the windows "orb"
when it should show me the windows "orb the screen boes blank and to standby.
but the computer just goes on with the boot.
when i boot to safe mode, no problem
when i reactivate the onboard graphics (ati), connect the screen to that connector, and install the ati drivers, no problem.

to make a long story short; does anybody had the problem that vista SP1 gives problems with the nvidia drivers?
because when vista SP1 starts loading the nvidia driver, it stops outputting anything to my screen.

also, sp1 broke a lot of shortcuts on my start menu, like complete office 2007 set (it is still installed and working, but shortcuts doesn't work anymore?) diskeeper, nero,..


before SP1 i had never a problem

i wonder, how long have they tested SP1 before roll-out?