I believe ImgBurn 2.4.3 has a new problem with my LiteOn LH-20A1H with firmware LL0D burning double-layer DVDs on Memorex 8x media. With 2.4.2 I got 100% success rate burning double-layer DVDs, but today I upgraded to 2.4.3 and produced 4 coasters in a row. I uninstalled 2.4.3 and reinstalled 2.4.2 and I'm back to 100% success rate.
Let me know what other information I can provide. Unfortunately I wasn't smart enough to save the log. If necessary I can sacrifice another DVD+R DL if that would be valuable. I have no other DVD+R DL media to cross-compare.