I have a desktop running WinXP & a Canon MP620 printer. Everything working fine until I ungraded to version 27.01, printer stopped working in Firefox but functioning with all other programs & browsers. Have the latest drivers for printer & have run extensive diagnostics with no luck. Downgraded to version 26.0 & printer started working again. As soon as I "upgraded" to version 27.01 again, printer stopped working in Firefox only...All the other solutions in support tried with no luck other than the downgrade & remain in version 26.0.