Sorry to have taken so long to reply. My laptop crashed, and it took Compaq forever to get it back in shape, but that's for another newsgroup.
I took my 190E to the dealership, and they could not find a problem. As I mentioned earlier (and to the dealership), when the fuse on the overprotection relay is removed, the car will recover for a while before acting up again. The first thing they did was to remove that fuse, and clearly, they could not find a problem since it did not exist. Anyway, they didn't charge me for it, so I can't complain.

I'll bring it back to the dealer and post again when the problem acts up and they identify it. Take care.