Richard Geller wrote:

 >Since you presented this problem it has always sounded a lot like very mild
 >food poisoning. )I get the same problem infrequently and attribute it to
 >something bad in the food I ate.) Is there a commonality to where you get
 >the greens, or the type of greens, or how you prepare them?

In the rec.travel.caribbean newsgroup a woman posted about her family's
experiment. Seems every year they go to Mexico, and despite not drinking
the water, they all would get sick. So this year they avoided all salad,
and fruit with peels that would be rinsed and then eaten. They didn't get
sick, except for one family member that tried the salad bar one day, at the
urging of a fellow tourist. Now Todd doesn't live in Mexico, but this seems
so similar.

Don.