I use ubuntu 12.04 with firefox and adobe pdf plugin. Since ubuntu 11.04 upto 12.04 i have the problem that i can open only one pdf file in the browser. After closing the pdf, firefox only shows a blank (black) screen when opening a new pdf. Ridiculous: As long as i keep open the first pdf, i can open other pdfs. Otherwise it seems to crash...
I already tried reinstalling, but nothing changed.