Running FF8.0 I cannot print a pdf file when the file is contained in a separate window opened by the appl (not just another tab). Options -> options -> applications all point to Use Adobe Applications in Firefox. I've had this problem in 7.0, 6.0, etc but I believe I was finally able to print these external browser/adobe windows somehow. Printing a pdf file shouldn't be that tough. When I run into this situation, file can be printed from the external window by IE.