I suspect my mmc drive not working properly. Could someone do this test for confirm it?
- Boot from a live USB (ubuntu, sparky, mint, fedora...).
- Open a terminal:
sudo su
cd /media/HERE-YOUR-PARTITION-IN-JAGUARBOARD
dd if=/dev/zero of=DELETE bs=1M

- Open another terminal:
watch df

Last is for watching changes in the mmc jaguardboard partition.

In my case, past 10 seconds or less it stops and I can't access to mmc. And when I try to turn off the system I get a lot of errors in diferent sector from mmcblk0p2 partition.

This issue is very annoying because I can't install large system in my JaguardBoard, if the installation requires a constant and prolonged writing in the mmc partition, it stops and leaves the installation uncompleted.

I Suggest you install a real linux system on it and test running some apps.

Or try my commands:
dd if=/dev/mmcblk0 of=/dev/null bs=1M count=1000
dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=1000

I tried many many times, no problem!

I'll try your tests, but I have a lot of problems to install distributions in the mmc, that is the reason I use external liveUSBs.
Today I tryed to install Deepin Linux, Linux Mint (Debian) and Sparky Linux. Deepin freezes while is copying files (I can not even move the mouse), and Mint throws me this message "Error 21 Is a directory: /target/usr/share/bug/udev" in the middle of installation. And Sparky Linux stopped and when I tryed to reboot it I got meessages like those:
mmc0: Timeout waiting for hardware interrupt
mmc0: Got data interrupt 0x02000000 even though no data operation was in progress.
mmc0: error -110 transfering data, sector 28833667, nr 5, cmd response 0x900, card status 0x0

Despite all this, I'm not 100% sure that the problem is the mmc, because today I've done a "dd" test in a pendrive and the system frozen too :-/

Maybe you can have a try with this guide:
www.jaguarboard.org:8090/display/ED/Turn...HD+Multimedia+Player

I see nothing particularly interesting in that guide.

Just for testing if the board is working fine or not.
If working fine with OpenELEC, then it is because of wrong way to install the linux.