As soon as I got a Surface Pro 3, I installed the MS Office 2013 suite of programs. I also installed a microSDXC memory that was formatted as exFat.
Frequently (three or four times a week) the MS Outlook program would give an error message and not be able to function. The only work around I found was to run the CHKDSK program on the microSDXC memory. This always worked. In fact it worked so often that the microSDXC memory ceased to function.
I then bought a new microSDXC memory and had exactly the same experience ONCE. I immediately reformatted the microSDXC to the NTFS standard and no more problem!

Anyone else have this experience?