I recently drove a ~90 mile trip without incident. The following day, on starting the car (1998 passat 20v turbo), the car shuddered semi-violently and the check engine light came on and stayed on. The shuddering stopped after a few seconds. I have yet to drive the car, but have started the car since then a couple times without any problems (except the check engine light is still on). First, is it safe to drive? Second any thoughts as to the problem?

The easiest ting to do is have the code checked. If the light is flashing you shouldn't drive it, if it's on steady it can be driven until checked.