Documents opened with Firefox won't print or even appear in preview. The document can be viewed but won't print. When trying to print (or see in preview) only a blank page appears. This happens even when the document is saved or made a PDF file. This began with 3.6.13 and continues with 3.6.15. Curiously, documents saved or made a PDF before this began ~ 2 weeks ago can be still be printed and viewed in preview. I'm using an iMac with OS X 10.6.6 and a CanonMX 300 printer