Can no longer print reduced size pagess exactly where I want them on a sheet.
Using Firefox 18.0 on XP Pro SP3 (up-to-date as far as I know)
This problem began suddenly on or about 01/12/2013.
There may have been some auto updates. (Looking at dates on Program Files directories, I see Mozilla Firefox was changed 1/11/2013 at 0901, so this may be a new problem with 18.0.)
I for a couple years, I have been printing Sudoku puzzles at 70% or 80% reduction, setting margins in Page Setup, so that I can place the puzzle precisely where there is available white space on used paper of various sizes and in landscape or portrait orientation. Occasionally the result was not what I expected, but it always turned out that I had not set Page Setup parameters correctly, and easily resolved the problem. No longer.
I have found a trick to get Firefox to recognize and remember a selected or custom page size (such as Legal) from session to session which I make use of and may possibly be relevant.