PC restarting while switching views

Hi Guys and GalsThis is my first post here but long time visitor...Im hoping some of you maybe could help me with this annoying problem im having with FSX...Sometimes when i try to switch views using the "s" key, my PC restarts itself...Already did a reinstall, deleted the FSX.cfg, went back to old drivers but the problem persists,..my system:Athlon X2 4200+MSI 7600 512 MB VideoCard4MB RAMThanks in advance and have a nice day :-)