Help memory card issues

[dolf408]

My memory card is a sandisk 16GB sdhc class 2, my phone is a motorola droid A855. the problem is when I go to bed at night I put my phone on a docking station to charge overnight when I awake to find my phone telling me that my memory card has been removed and I am unable to unmount or to format it. When I take the card out and use it on my computer by way of a card reader all my music and files are there. When I use a USB cable, the computer does not see my phone or card but my droid says it is plugged in to a USB and is in debugging mode. I format it with the card reader and reinstall my music and apps and everything works fine, until I wake up the next day to see it telling me my SD card has been removed.