I would do a complete uninstallation using the instructions found at the bottom of this page http://www.aerofly.com/afpd/downloads.html and do a reinstallation. Then download and apply patch 1.8.0.25 if you do not have any addons, or patch 1.9.7.11 if you have addons 1 and 2. Your video card is too slow for addons 3 and 4. Please update your video card driver as well.