Glo problem with converting Mobi to ePub, won't read right.

I added my MOBI files to calibre, and pressed send to main device memory. The books look fine when I double click them in calibre but when I open it on my Kobo Glo it shows a white page with the top right corner folded, says it is at 99% and it makes my Kobo very slow while it is open (have to press home several times to get out of it).

Any idea how to fix this?

EDIT: This seems to be any Epub file I am adding. I tried adding a Epub with calibre that did not need converting and I am having the same problem?