Asterisk reboots during Calls

Hi,

i´m brand new here and have not mutch experience, so now i have a problem with it.

Everytime i make a Call, Asterisk reboots(1.2.24), sometimes the hole machine stucks.
I use the Grandstream GXP2000 Phones with FW 1.1.4.25.
Maybe someone has this Problem and know what is happend?

Update:
When i use the 2x 1xS0 Interface-Card(HFC) then it works, so it has to be the reason on the 2x 4xS0 Card.

Thx
Cpbx