hi,
I had got your problem a month ago. I use O2 Mini XDA with 2GB Store Card. I usually copy files to Store Card by the Card Reader, not copy them via Phone. One day, I'm lazy to put the Store Card out the phone and copy files from Store Card to PC about 1GB and then PC can not recognize any Store Card. I think the Store Card Reader of the phone has problem.

Bought a 2mg card for my new 6500 slide, dragged a few photos & mp3 tracks from my pc put in phone, but it wont recognise card, replaced original card that came with phone to find it wont recognise that card now, any one any ideas before i take it back
thanks in advance