Graphic card problem please help

hi i have recently installed nvida 8500gs on my vista ultimate ie just plug and play as someone suggested, my problem is when i turn of the pc and the next morning i turn it on i pust the turn on button and it makes a restart noice keeps repeatedly doing it with no display, as soon as i pull the vga wire from the graphics card and plug it back in it goes all ok but has become annoying because i have to do it when ever i turn the pc on.

i have an intergrated 6400 nvida card can some one please help me it was ok for the first week then it all started.
my pc specs are:
acer t1800
2.5gb ram
160gb harddrive (hitachi)
vista ultimate
i have ran mem test and harddrive no problem i can play games all day long no problem just when i turn pc on...

thanks for the help guys really appriciated it.

Did you uninstall the integrated graphics driver? and installed the new driver for the 8500gs card?

Also maybe you have to set in the BIOS menu to PCIx for display.

thanks ill try and get back