Mmm I think that you just had a batch of bad quality DL's, I am sure you have seen how many times we recommend Verbatim DVD+R DL's and it's for these reasons. 8 crap burns and then 3 good ones sounds about right to me.
You may not be convinced but I have never seen any issues with ImgBurn affecting other burning programs, the first thing we always do when trouble shooting is to check the media, your current choice is poor and whislt it may be cheap is it worth these hassles ?
My first step would be to buy Verbatim DVD+R DL media and burn it at 2.4x.