rebooting with v58 message

I just move and got a new Comcast account with CableCard. Had problems with the 1st card as it was not able to be paired to my box. Now with 2nd card my Premiere box is rebooting often (atleast a few times a day) and get the occasional V58 not authorized message -couldn't even watch the game last night. :(
Does it sound like I got another bad card? or is my hard drive going out?

Note previously I was on another Comcast account with another CableCard with no issues. And I'm using ethernet connection

Thanks in advance for any help