I can see the ISOs now... there weren't any 0 byte ISO files appearing before. I was using "BROWSE" to get the the directory to create it.
I tried typing a direct path instead (D:\TempISO), and it created an empty ISO, and I was able to burn several successful ISOs after that.
Browsing to the write destination works as well, ever since...
Strange, but I'm happy with that. It works perfect every time now.