Error Message on game startup: There was an error during startup. Please see the log for more details!!

When i launch the Sims 3 game launcher a error message comes up saying There was an error during startup. Please see the log for more details. When i first downloaded sims 3 it worked perfectly for months and recently it comes up with that message. I've uninstalled it and re-downloaded and it worked but it messed up again and i've downloaded it again and it doesn't work. Please Help!!!!!!!!? Thank youuuuuu.