We use USPS Click & Ship to print labels for shipping our products. Been using it for several years and have had no problems with FF 3.x todate. Recently we upgraded to FF4.x and we are having intermittent problems at the stage of actually printing the labels. The USPS takes the labels and turns them into a PDF, then pops-up a dialog box to print the labels. "Intermittent" means, sometimes the PDF print pop-up shows up and sometimes it does not. This problem seems to be isolated to FF4 only because we can use FF3.x, Chrome, and IE. Also, it seems as though the more labels we print, the more likely it is to happen (if we print 10 labels, it happens most often, if we print fewer, it does not happen as often) Will be reporting this to USPS as well, but wondered if any one here would have any insight into why this might be occurring only in the new FF4.