Confirmed in 64-bit Kubuntu with Firefox 3.6.10.
No file open/save dialog ever appears. But it works, when evoked by shortcut. For example: pressing File->Save Page As... (by cursor) does nothing. But pressing Ctrl+S opens <Save Page As...> dialog. kmozillahelper is not installed. I had the same problem with Kubuntu 10.04.
Confirmed in 64-bit Kubuntu with Firefox 3.6.10.
No file open/save dialog ever appears. But it works, when evoked by shortcut. For example: pressing File->Save Page As... (by cursor) does nothing. But pressing Ctrl+S opens <Save Page As...> dialog. kmozillahelper is not installed. I had the same problem with Kubuntu 10.04.