This is a problem I had too and contacted nVidia support. The following is the reply I received and resolved the problem for me:
Please visit the given below link and run driver cleaner application that will remove corrupted and unwanted files from the system registry. After running the driver cleaner application un install the existing driver version and install 96.85 driver version for NVIDIA GeForce 7600 Graphics card on Windows Vista operating system in Safe mode.
Driver cleaner Link:
Please visit the link given below to download the driver and click on save button, the driver will get downloaded into your computer by itself.
Windows VISTA 32 bit
Windows VISTA 64 bit