I forgot where I found this workaround, it worked on Karmic 64bits: Open terminal and enter: gksudo gedit /usr/lib/nspluginwrapper/i386/linux/npviewer
then add: export GDK_NATIVE_WINDOWS=1 before the last line of text
I forgot where I found this workaround, it worked on Karmic 64bits: nspluginwrapper /i386/linux/ npviewer
Open terminal and enter:
gksudo gedit /usr/lib/
then add: export GDK_NATIVE_ WINDOWS= 1 before the last line of text