When you install your next NVIDIA version, boot into Safe Mode by repeatedly pressing the F8 key once the ASUS Splash Screen is displayed. Choose the "Custom" install option for the NVIDIA driver installation, and be sure to check the "Clean Install" checkbox. By installing from Safe Mode, you will eliminate running drivers that could potentially interfere with the installation. The NVIDIA "clean install" option will uninstall your previous driver installation and hopefully eliminate problems for the subsequent installation.
You could also try using Windows System Restore to restore your system to an earlier time when it was stable, then retry the NVIDIA driver update from Safe Mode.
G74SX-A1 - stock hardware - BIOS 202 - 2nd Monitor VISIO VF551XVT