I had that experience before. If you put a phone and other cards like bank card together, the card may become useless. Don't do that.
I'll keep this simple. I've had problems with several Droid cell phones going screwy on me and was wondering if it's caused by the magnets that keep women's purses closed. I know the purse I'm using now has an extremely strong one and I find things clinging to it all the time. If this is the case, women should be warned.