starting trouble - grinding noise

Hi guys,

Another problem with my car (190E 2.3, 1985, 116K) - sometimes, the car doesn't start, and a sharp, loud grinding noise comes. The second time (or the third/fourth, sometimes) it starts up. Then the problem won't happen for a week or so, then happens again. It has been going on like this for two years now, except that yesterday, it just didn't start! after 12-13 tries, it finally started - usually it takes only a couple of grinds, if it happens. I am worried I might get stalled somewhere. What could the problem be? Is it something major? IF yes, when I get it done, are there other things that I should get done as well, since the car would be opened up anyways?

Appreciate all your help, thanx,
Rags.