1997 Hyundai Sonata cutting out

Engine Mechanical problem
1997 Hyundai Sonata Manual 93000 miles

Hi there,
Our car has done this twice now.
All of a sudden when we are driving along it will shiudder then lose all its power.
We have to pull over to the kerbside.
It has also failed to start promptly on two occasions (are the incidents connected
What could be the problem.
We want to use the motorway in June for our hols,
but not with a car that cuts out.
I look forward to your reply

updated 6/9/09
Hi there, you replied to ask me if the light was coming on, on the dashboard.
No it is not coming on.
The car is tootling along, then it just judders and seems to go into neutral (it is an automatic)
We have to pull over and switch off, then restart after a while.
Do you think it could be the gear box.
Thank you