MSTS HELP

hi i had to re install msts due to my cmputer playing up whe n i clik to load the game up when i comes to the screen with the green background and train in background and the bar at the bottoms scans to load up the main home page after about halfway i get that error message that says msts has encoutered a problem and needs to shut down how do i overcome this i remember doing it before but i t was ages ago???