muliblitz power packs

[merc]

Hi all does any out there use multiblitz power packs?The reason i ask i that the studio where i work bought 2 brand new muttiblitz 2400 power packs last summer and we have had them back to germany twice already.The problems include packs freezing ,varying power displays and most disturbing the packs are arcing(loud bangs like gunshots}.We have olderpacks which seem to be more reliable.Anyone have similar problems?.Its not a power supply problem as it has happened on location.