I found a solution to this problem, it works for me and I hope it will work for you,
1. Unmount your SD card (menu, settings, sd card and storage, click on "unmount SD card"
2. Once this is completed and it shows to be unmounted, download and install Angry Birds or whatever app is vexing you.
3. After all the installation stuff is done, remount you SD card using the reverse method in 1.
My wife has the identical Droid X that I have and her's works just fine. :wacko:Anyway, try this and post your results here. Good Luck to All
Long Live The Empire!!