XBMC does not run

[PG78420]

Hi All,

After 3 days using the matrix, I meet different issues:
1)The sound card looks working strange with my HC amp (hdmi connected), means that the voices are in the left rear speaker and not in the central one!!!!!
2)Since yesterday , matrix doesn't run XBMC at all. When I start the matrix, the 1st screen with the message "bla bla bla ...after 3 sec xbmc will start" appears and after, nothing, black screen. I look at the boot menu and test the matrix with no issue.

As my technical bacgroung is poor, do you have an idea/solution to those 2 problems

THX in advance for your help