I'm pretty sure the flashing SES light means it's misfiring. I'm not 100% sure, somebody will chime in. Either way you need to pull the code. Autozone does it for free. There's a list of codes in the Write Up section here.
yea when it flashes i was told by my mechanic that its not good and you should not drive it. when i had a bad ignition coil which causes the engine to misfire it did the same thing to me maybe change one of the ignition coils
+1 When your check engine light is flashing you should turn the car off immediately and have it towed wherever you need too. Its misfiring so bad it could destroy your cats and your engine.