Hi maximo,
another guy with CV643D problem!!
So, have you removed (Uninstall) P96 before install CGX3?
P96 has an uninstaller as well.
As suggested at other guys, remove again all the CGX3 (ancient) related driver/libs and install again P96.
During the installation, the installer ask you the max freq H-V supported by your monitor.
Choose: 80 Hz for VERTICAL
80 Khz for HORIZZONTAL
Even if your monitor can accept higher freq., remember that your GFX board has only 4 MB of VRAM.
Ciao