The invisible Boot Menu... NVDIA GeForce 7800 GS

I have setup vista succesfully (eventually)

Now, I have a black screen at boot time.
However the BOOT CHOICES menu IS there, just not displayed on the monitor...
so pressing enter or UP/DOWN then enter still works to instantiate OS's...
(multi boot system obviously) I just have to remember to do the right
keystrokes blindly and it works...

NVDIA GeForce 7800 GS...
Using the nvlddmkm.sys driver.

Anyone else getting this issue?
Thanks
CyberMan