Firefox 37.0.1 on Windows 7 64 bit. To try to fix, I have inactivated all addons, then removed all addons, then back leveled Firefox, then uninstalled Thunderbird (as this was an addition around the time this started happening), and deleted and reinstalled the printer driver. Even when I uninstalled Thunderbird and then installed Firefox 37.0.1 I cannot print. With both programs reinstalled now I again cannot print from either. I get "error encountered while printing" with Thunderbird, and a crash with Firefox. I followed all of the advice in the "Fix printing problems in Firefox" article in the knowledge base to no avail. The latest Firefox crash report is bp-1132bb48-c14b-4f20-ab65-8d58e2150415. Looking below, I see that there are installed plugins, but I don't understand how those got there as I completely uninstalled, downloaded, and reinstalled Firefox. I can't find the same issue in the knowledge base and can't fix following printer problem suggestions. Sure would appreciate some help. I also reset all print related config entries per advice in another support thread. Many of those were MP560 related and had that model name built into the config entry name (my printer is a Canon MP560). I notice now that those entries are missing. I also have no PRINT_PRINTER entry referenced as a config option to reset. It is missing. Resetting the PRINT.PRINT_PRINTER entry on Thunderbird also did not work and the entry disappeared upon reset. I believe this is what happened with Firefox, too. I forgot to say that I can print fine from all other programs and browsers.