If you have the problem of opening PDF document in Firefox browser and then the browser just hangs or gets the error message
"Acrobat is still displaying a document in a browser. are you sure to want to quit? [Y] [N]"

The solution is not using the firefox plugin to open pdfs in the browser at all.

go to Tools-->Options-->Downloads-->Plugins and disabled the pdf plugin.

Then click on a link to a pdf document, Firefox asked what program to use, selct acrobat reader executable file

edit @ 2005/09/24 00:13:00