problem with mkv videos

Hi team.

Iv just upgraded my 16.1 (its worked prfectly) to v17 krypton.
First big problem what I found is krypton have some problem with mkv files.
avi works good, but when i tried to play some mkv files screen is black with some small “x” on the middle, and then krypton going back to start menu.
someone had that issue?
thanks for help
regards