I certainly understand your frustration.
The good news is that this problem is not encountered all that often by our user base. The reason why some of us knew the solution so quickly is simply due to our intimate familiarity of the internal advanced printing dialogs and all the gazillion obscure options there. (Yes, I know that we ought to get a life! )
There are only two ways we know of this Print to File option being set. The first is what we outlined above, possibly a side affect of clicking or attempting to click on the nearby Print as Image option. The other way is to set the port of the printer itself to File in the OS Printer Properties.
I'll pass along your suggestion about documenting this issue in the Help topics. Might take a while, though.
- Dov