Double Layer DVD+R burning problem - I/O Error

Double Layer DVD+R burning problem - I/O Error

I have a modern PC (Quad Core CPU, 4 GB RAM, Win7 Home Premium 64-bit) but I have a problem with burning .dvd images to Double Layer (8.5 GB) DVDs. I wasted too many DVD+R DL discs but to no avail. Here is a short explanation of what I did: