CBR8 Channel bonding issue

Hi ,
I am using CISCO CBR8 CMTS using 8 DS with 2 U/S channel bonding . Issue is that , modem is releasing both D/S and U/S channel bonding and locking on singh D/S and U/s channels however RF level is ok with good SNR. On restart of cable modem is locks all 8 D/S and 2 U/s for some time and after couple of hours same issue. This issue is across all ports/ Line cards

Pl help.