A large number of vendors list items are missing from my comodo v5, only less than twenty items left.
This happens on several computers in our labs.
Why this happens? and are there some ways to backup my Trusted Software Vendors list?
I believe there was a bit of a hiccup at Comodo. I suspect they’ll put measures in place to ensure this doesn’t happen again, but if you’d like to back the list up, your vendors list hangs out in C:\Program Files\COMODO\COMODO Internet Security\database
Oh, Thanks! 
Expecting Comodo will become more perfect.