I don't know if this will apply to you or not, it certainly won't be of any help because I never did figure out how to fix it.
Anyway, I have my hubby's yahoo email and calendar set up on my phone. I noticed that in those settings there was an option to turn on Reminders. I thought, oh cool, if we set up reminders on our phones, it will be pushed to each others phone like the calendar. Not. In Reminders, there was a page listed with his email addy on it and everytime I would add something to that page it would disappear. A couple of days later a couple of pages showed up in Reminders on his phone with a huge string of number and letters in the heading where the email address had been. I never did get it to work right and just turned it off on both phones. I don't know if what I was tryng to do was just wishful thinking or if it was a glitch. I think odds are its about 50/50.